Conductive material dispersion liquid, conductive film, and method for producing conductive material dispersion liquid

Abstract

To provide a conductive material dispersion liquid enabling formation of a conductive film having both transparency and conductivity.SOLUTION: A conductive material dispersion liquid containing a carbon-based conductive material (A), a dispersant (B), and a dispersion medium (C). The carbon-based conductive material (A) includes multilayer carbon nanotubes (A-1), the content of iron in the multilayer carbon nanotubes (A-1) being more than 0 mass% and 5 mass% or less, and the total content of cobalt and molybdenum being 0 mass% or more and 0.1 mass% or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a conductive material dispersion. [Background technology]

[0002] Transparent conductive films used in displays, solar cell electrodes, electromagnetic wave shielding materials, etc. must be both transparent and conductive, and ITO films have been used for this purpose. However, to reduce costs, conductive material dispersions, in which conductive materials are dispersed in liquid, have been developed.

[0003] For example, Patent Document 1 discloses a carbon material dispersion containing at least two types of carbon materials selected from the group consisting of single-walled carbon nanotubes, multi-walled carbon nanotubes, and carbon black, an aqueous medium, a dispersant, and a binder resin. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7230269 Summary of the Invention [Problem to be solved by the invention]

[0005] Generally, single-walled carbon nanotubes have higher conductivity than multi-walled carbon nanotubes, but their high price makes it difficult to reduce the cost of conductive films. Furthermore, single-walled carbon nanotubes are thin, with a diameter of 1-2 nm, and are prone to agglomeration. Therefore, agglomerated foreign matter and uneven coating remain in the conductive film coated with the dispersion, resulting in problems of reduced transparency. On the other hand, multi-walled carbon nanotubes have the problem of reducing the transparency of the conductive film because they must be used in large quantities to achieve the desired conductivity, while carbon black has the problem of insufficient conductivity despite its high dispersibility and stability. Therefore, conventional dispersions have not been able to achieve both conductivity and transparency.

[0006] An object of the present invention is to provide a conductive material dispersion liquid that can form a conductive film that is both transparent and conductive. [Means for solving the problem]

[0007] <1> A conductive material dispersion containing a carbon-based conductive material (A), a dispersant (B), and a dispersion medium (C), The carbon-based conductive material (A) contains multi-walled carbon nanotubes (A-1), A conductive material dispersion liquid in which the iron content in the multi-walled carbon nanotubes (A-1) is more than 0 mass% and 5 mass% or less, and the total content of cobalt and molybdenum is 0 mass% or more and 0.1 mass% or less. <2> The specific surface area of ​​multi-walled carbon nanotubes (A-1) is 400m 2 / g or less, <1> Conductive material dispersion liquid. <3> The average aspect ratio of the multi-walled carbon nanotubes (A-1) is 300 or more and 2000 or less. <1> or <2> Conductive material dispersion liquid. <4> The average outer diameter of the multi-walled carbon nanotubes (A-1) is 5 nm or more and 30 nm or less. <1> ~ <3> Any of the conductive material dispersions. <5> The content is 0.01% by mass or more and 5% by mass or less in 100% by mass of the nonvolatile content of the conductive material dispersion liquid. <1> ~ <4> Any of the conductive material dispersions. <6> The dispersant (B) contains at least one dispersant selected from the group consisting of nonionic dispersants, anionic dispersants, cationic dispersants, and amphoteric dispersants. <1> ~ <5> Any of the conductive material dispersions. <7> The conductive dispersion has a thixotropy index of 2 or more and 10 or less. <1> ~ <6> Any of the conductive material dispersions. <8> The D50 particle size of the conductive dispersion is 10 μm or more and 150 μm or less. <1> ~ <7> Any of the conductive material dispersions. <9> Further containing a resin (E), <1> ~ <8> Any of the conductive material dispersions. <10> Further containing non-conductive particles (F), <1> ~ <9> Any of the conductive material dispersions. <11> the content of the carbon-based conductive material (A) is 0.01% by mass or more and 3% by mass or less in 100% by mass of the nonvolatile content of the conductive material dispersion; <1> ~ <10> Any of the conductive material dispersions. <12> A conductive film containing a carbon-based conductive material (A), a dispersant (B), and a resin (E), The carbon-based conductive material (A) contains multi-walled carbon nanotubes (A-1), A conductive film, wherein the iron content in the multi-walled carbon nanotubes (A-1) is greater than 0 mass % and not more than 5 mass %, and the total content of cobalt and molybdenum is 0 mass % or more and 0.1 mass % or less. <13> The resin (E) is a binder resin. <12> Conductive film. <14> A method for producing a conductive material dispersion liquid obtained by dispersing a mixture containing a carbon-based conductive material (A), a dispersant (B), and a dispersion medium (C) using a media-less disperser selected from the group consisting of a rotor-stator type disperser, an ultrasonic disperser, and a high-pressure homogenizer, comprising: The carbon-based conductive material (A) contains multi-walled carbon nanotubes (A-1), A method for producing a conductive material dispersion, wherein the iron content in the multi-walled carbon nanotubes (A-1) is more than 0 mass% and 5 mass% or less, and the total content of cobalt and molybdenum is 0 mass% or more and 0.1 mass% or less. <15> A method for producing a conductive material dispersion liquid containing a carbon-based conductive material (A), a dispersant (B) and a dispersion medium (C), wherein the carbon-based conductive material (A) contains multi-walled carbon nanotubes (A-1), The iron content in the multi-walled carbon nanotubes (A-1) is more than 0% by mass and 5% by mass or less, and the total content of cobalt and molybdenum is 0% by mass or more and 0.1% by mass or less, A method for producing a conductive material dispersion liquid, comprising the following step (a): Step (a): A step of preparing a mixed solution by mixing a carbon-based conductive material (A), a dispersant (B), and a dispersion medium (C), and then dispersing the mixed solution at a pH of 7 or higher. [Effects of the Invention]

[0008] The present invention provides a conductive material dispersion capable of forming a conductive film that is both transparent and conductive, and also provides methods for producing the conductive film and the conductive material dispersion. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described in detail below. In this specification, "another carbon-based conductive material (A') other than the multi-walled carbon nanotubes (A-1)" may be referred to as "a carbon-based conductive material (A')". Furthermore, in this specification, when "(meth)acrylic", "(meth)acryloyl", "(meth)acrylic acid", "(meth)acrylate", and "(meth)acryloyloxy" are written, they respectively mean "acrylic or methacrylic", "acryloyl or methacryloyl", "acrylic acid or methacrylic acid", "acrylate or methacrylate", and "acryloyloxy or methacryloyloxy", unless otherwise specified. The particles are not limited to spherical particles and include particles having an aspect ratio. Furthermore, unless otherwise noted, the various components appearing in this specification may be used independently either alone or in combination of two or more. The TI value indicates the thixotropy index. CNT is an abbreviation for carbon nanotube. The numerical values ​​specified in this specification are values ​​determined by the methods disclosed in the embodiments or examples.

[0010] <Carbon-based conductive material (A)> The carbon-based conductive material (A) is a particle mainly composed of conductive carbon. The carbon-based conductive material (A) contains multi-walled carbon nanotubes (A-1) and may further contain other carbon-based conductive materials (A') other than the multi-walled carbon nanotubes (A-1).

[0011] <Carbon nanotubes> Carbon nanotubes are particles having a cylindrical or fibrous structure in which a planar graphene sheet is rolled up. Examples of carbon nanotubes include single-walled carbon nanotubes having a structure in which one layer of graphene sheet is rolled up, and multi-walled carbon nanotubes having a structure in which two or more layers of graphene sheet are rolled up. Carbon nanotubes may also have a partially amorphous structure. The carbon nanotubes in the present invention are classified into multi-walled carbon nanotubes (A-1), multi-walled carbon nanotubes other than the multi-walled carbon nanotubes (A-1) (A-2), and single-walled carbon nanotubes (A-3), which will be described later.

[0012] The shape of the carbon nanotube is not particularly limited, but examples thereof include needle-like, cylindrical, fishbone-like (fishbone or cup stacked type), trump-like (platelet), and coil-like shapes. Among these, needle-like and cylindrical shapes are preferred.

[0013] [Multi-walled carbon nanotubes (A-1)] The multi-walled carbon nanotubes (A-1) have an iron content of more than 0% by mass and 5% by mass or less, and a total content of cobalt and molybdenum of 0% by mass or more and 0.1% by mass or less. The iron is a component derived from the catalyst used in the synthesis of the multi-walled carbon nanotubes (A-1). Since iron-containing carbon nanotubes have a branched structure that contributes to electrical conductivity, they can achieve a high level of conductivity, transparency, and dispersibility all at the same time. The iron content of the multi-walled carbon nanotubes (A-1) is 5% by mass or less, preferably 4% by mass or less, more preferably 3% by mass or less, and even more preferably 1.5% by mass or less. The lower limit is not particularly limited, but is, for example, 0.1% by mass or more, more preferably 0.5% by mass or more. The total content of cobalt and molybdenum contained in the multi-walled carbon nanotubes (A-1) is 0% by mass or more and 0.1% by mass or less, preferably 0.05% by mass or less, more preferably 0.01% by mass or less, and even more preferably substantially free of cobalt and molybdenum. Note that "substantially" means not intentionally containing them.

[0014] In the total content (100% by mass) of metal components contained in the multi-walled carbon nanotubes (A-1), the total content of cobalt and molybdenum is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 2% by mass or less.

[0015] The multi-walled carbon nanotubes (A-1) can be synthesized by chemical vapor deposition, arc discharge, or laser sublimation, among which chemical vapor deposition is preferred.

[0016] The metal components other than cobalt and molybdenum contained in the multi-walled carbon nanotubes (A-1) are preferably in the form of particles, with an average primary particle diameter of preferably 1 nm to 50 nm, more preferably 3 nm to 40 nm, and even more preferably 5 nm to 30 nm. The average primary particle diameter of the metal components contained in the multi-walled carbon nanotubes (A-1) can be obtained by observing with a transmission electron microscope, randomly selecting approximately 20 particles, measuring their particle diameters, and calculating the number average value.

[0017] The powder resistivity of the multi-walled carbon nanotubes (A-1) is preferably 0.02 Ω cm or less, more preferably 0.015 Ω cm or less, and even more preferably 0.01 Ω cm or less. The lower limit of the powder resistivity is preferably as low as possible, but the lower limit is preferably 0.001 Ω cm or more. The powder resistivity of the multi-walled carbon nanotubes (A-1) was measured by compressing 1.0 g of powder under a load of 25 MPa, and then using a resistivity meter (Loresta-GX MCP-T700 manufactured by Mitsubishi Chemical Analytech Co., Ltd.) and a powder resistivity system (MCP-PD51 manufactured by Mitsubishi Chemical Analytech Co., Ltd.: four-point probe-ring electrode, electrode spacing 5.0 mm, electrode radius 1.0 mm, sample radius 12.5 mm).

[0018] The average outer diameter of the multi-walled carbon nanotubes (A-1) is preferably 1 nm or more, more preferably 5 nm or more, and even more preferably 10 nm or more. The average outer diameter is preferably 50 nm or less, more preferably 30 nm or less, and even more preferably 20 nm or less. Although the multi-walled carbon nanotubes (A-1) may form a bundle structure by gathering multiple particles, the average outer diameter is the value of each individual primary particle. The average outer diameter of the multi-walled carbon nanotubes (A-1) can be obtained by observing the morphology of the carbon nanotubes using a transmission electron microscope at a magnification of 50,000 times, randomly selecting approximately 20 carbon nanotubes, measuring the length of their minor axes, and calculating the number average value.

[0019] When a plurality of multi-walled carbon nanotubes (A-1) form a bundle structure, the average bundle diameter is preferably 5 nm or more, more preferably 10 nm or more, and even more preferably 15 nm or more, and is preferably 70 nm or less, more preferably 50 nm or less, and even more preferably 30 nm or less. The average bundle diameter of the multi-walled carbon nanotubes (A-1) can be obtained by observing the morphology of the carbon nanotubes at a magnification of 50,000 times using a transmission electron microscope, randomly selecting approximately 20 carbon nanotubes, measuring the lengths of their minor axes, and calculating the number average value.

[0020] The average fiber length of the multi-walled carbon nanotubes (A-1) is preferably 0.1 μm or more and 50 μm or less, more preferably 0.5 μm or more and 40 μm or less, and even more preferably 1 μm or more and 20 μm or less. The average fiber length of the multi-walled carbon nanotubes (A-1) can be obtained by measuring the fiber lengths of approximately 20 randomly selected carbon nanotubes using a scanning electron microscope at a magnification of 10,000 times and calculating the number average value.

[0021] The average aspect ratio of the multi-walled carbon nanotubes (A-1) is preferably 100 or more and 2000 or less, more preferably 150 or more and 1500 or less, and even more preferably 200 or more and 1000 or less. When the aspect ratio is 100 or more, the contact resistance between CNTs is reduced, and conductivity is easily exhibited. Furthermore, when the aspect ratio is 2000 or less, a dispersion with good fluidity can be obtained. The average aspect ratio of the multi-walled carbon nanotubes (A-1) can be calculated by dividing the average fiber length by the average outer diameter.

[0022] The specific surface area of ​​multi-walled carbon nanotubes (A-1) is 100m 2 / g or more is preferable, and 150m 2 / g or more is more preferable, and 200m 2 / g or more is more preferable. 2 / g or less is preferable, and 400m 2 / g or less is more preferable, and 300m 2 The specific surface area in the present invention is a BET specific surface area, which can be calculated by the BET multipoint method using a nitrogen adsorption method. 0.03 g of multi-walled carbon nanotubes (A-1) were weighed using an electronic balance (Sartorius, MSA225S100DI) and then dried at 110°C for 15 minutes while degassing. The specific surface area (m ) of the multi-walled carbon nanotubes (A-1) was then determined by measuring the amount of nitrogen adsorption using a helium-nitrogen mixed gas (helium:nitrogen = 7:3) using a fully automatic specific surface area measuring device (MOUNTECH, HM-model1208). 2 / g) can be obtained.

[0023] By setting the average outer diameter, average fiber length, specific surface area and average aspect ratio of the multi-walled carbon nanotubes (A-1) within the above ranges, it is possible to achieve both high dispersibility and high conductivity.

[0024] The G / D ratio of the multi-walled carbon nanotubes (A-1) is preferably 0.1 or more and 3.0 or less, more preferably 0.3 or more and 2.0 or less, and even more preferably 0.5 or more and 1.0 or less. The G / D ratio is an index of the crystallinity of carbon nanotubes and can be obtained by Raman spectroscopy. -1 More than 1600cm -1 The maximum peak intensity of the G band derived from graphite measured in the following range is 1310 cm -1 More than 1350cm -1 It can be calculated by dividing by the maximum peak intensity of the D band derived from amorphous carbon measured in the range below. A higher G / D ratio indicates a higher degree of crystallinity and therefore better conductivity. The laser wavelength used in Raman spectroscopy is 532 nm.

[0025] From the viewpoint of electrical conductivity, the purity of the multi-walled carbon nanotubes (A-1) is preferably 95% by mass or more, more preferably 96% by mass or more, and even more preferably 97% by mass or more, based on the mass of the carbon nanotubes. The ash content of the carbon nanotubes is preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 3% by mass or less. The purity of the carbon nanotubes is expressed as the value (% by mass) obtained by subtracting the ash content (% by mass) from the mass of the carbon nanotubes. The ash content (% by mass) of the carbon nanotubes can be measured, for example, in accordance with JIS K 6218-2.

[0026] The pH of the multi-walled carbon nanotubes (A-1) is preferably 7.5 or higher, more preferably 8.0 or higher. The pH of the carbon nanotubes is measured with a pH meter after preparing a suspension by adding 1 g of carbon nanotubes to 50 g of ion-exchanged water at 25°C and treating the suspension with an ultrasonic cleaner for 10 minutes.

[0027] Commercially available multi-walled carbon nanotubes (A-1) include, for example, ATHLOS manufactured by Cabot Corporation.

[0028] The content of the multi-walled carbon nanotubes (A-1) in the carbon-based conductive material (A) is preferably 10 to 100 mass%, more preferably 20 to 100 mass%, further preferably 50 to 100 mass%, particularly preferably 80 to 100 mass%.

[0029] [Multi-walled carbon nanotubes (A-2)] The multi-walled carbon nanotubes (A-2) are multi-walled carbon nanotubes other than the multi-walled carbon nanotubes (A-1), and the total content of cobalt and molybdenum is preferably more than 0.1% by mass and not more than 5% by mass, more preferably 0.5% by mass or more and 4% by mass or less, and even more preferably 1% by mass or more and 3% by mass or less. In one embodiment, the conductive material dispersion of the present invention may further contain multi-walled carbon nanotubes (A-2).

[0030] The average outer diameter of the multi-walled carbon nanotubes (A-2) is preferably 3 nm or more, more preferably 5 nm or more. Also, it is preferably 30 nm or less, more preferably 20 nm or less. Although the multi-walled carbon nanotubes (A-2) may form a bundle structure by gathering multiple particles, the average outer diameter is the value of each individual primary particle. The average outer diameter of the multi-walled carbon nanotubes (A-2) can be obtained by the same method as that for the multi-walled carbon nanotubes (A-1).

[0031] The average fiber length of the multi-walled carbon nanotubes (A-2) is preferably 0.1 μm or more and 200 μm or less, more preferably 1 μm or more and 100 μm or less, and even more preferably 3 μm or more and 50 μm or less. The average fiber length of the multi-walled carbon nanotubes (A-2) can be obtained by the same method as that for the multi-walled carbon nanotubes (A-1).

[0032] The average aspect ratio of the multi-walled carbon nanotubes (A-2) is preferably 100 or more and 10,000 or less, more preferably 250 or more and 5,000 or less, and even more preferably 500 or more and 2,000 or less. The average aspect ratio of the multi-walled carbon nanotubes (A-2) can be obtained by the same method as that for the multi-walled carbon nanotubes (A-1).

[0033] By setting the average outer diameter, average fiber length and average aspect ratio of the multi-walled carbon nanotubes (A-2) within the above ranges, it is possible to achieve high levels of both dispersibility and conductivity, which is preferable.

[0034] Commercially available multi-walled carbon nanotubes (A-2) include, for example, JENOTUBE10B (average outer diameter: 7 to 10 nm) and JENOTUBE6A (average outer diameter: 5 to 7 nm) manufactured by JEIO Corporation, FT7320 (average outer diameter: 7 to 11 nm) manufactured by Cnano Corporation, K-Nanos100P (average outer diameter: 10 to 15 nm) and K-Nanos100T (average outer diameter: 10 to 15 nm) manufactured by Kumho Petrochemical Co., Ltd., and BT1001M (average outer diameter: 10 to 15 nm) manufactured by LG Chem Ltd.

[0035] The content of the multi-walled carbon nanotubes (A-2) is preferably 0.1 to 100 parts by mass, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less, relative to 100 parts by mass of the multi-walled carbon nanotubes (A-1). By blending them in this ratio, the dispersibility is improved while maintaining the conductivity.

[0036] [Single-walled carbon nanotubes (A-3)] In one embodiment, the conductive material dispersion of the present invention may further contain single-walled carbon nanotubes (A-3).

[0037] The powder resistivity of the single-walled carbon nanotubes (A-3) is preferably 0.02 Ω cm or less, more preferably 0.01 Ω cm or less, and even more preferably 0.005 Ω cm or less. The lower the resistivity, the better, so there is no particular lower limit, but it is, for example, 0.0001 Ω cm or more. The powder resistivity of the single-walled carbon nanotubes (A-3) can be obtained in the same manner as that of the multi-walled carbon nanotubes (A-1).

[0038] The average outer diameter of the single-walled carbon nanotubes (A-3) is preferably 1 nm or more, more preferably 1.5 nm or more, and even more preferably 2 nm or more. It is also preferably 10 nm or less, more preferably 5 nm or less, and even more preferably 3 nm or less. Although the single-walled carbon nanotubes (A-3) can form a bundle structure by assembling multiple particles, the average outer diameter is the value for each individual primary particle. The average outer diameter of the single-walled carbon nanotubes (A-3) can be obtained by observing the morphology of the carbon nanotubes under a transmission electron microscope at a magnification of 100,000 times, randomly selecting approximately 20 carbon nanotubes, measuring the length of their minor axes, and calculating the number average value.

[0039] The average fiber length of the single-walled carbon nanotubes (A-3) is preferably 0.1 μm or more and 200 μm or less, more preferably 1 μm or more and 100 μm or less, and even more preferably 3 μm or more and 50 μm or less. The average fiber length of the single-walled carbon nanotubes (A-3) can be obtained by the same method as that for the multi-walled carbon nanotubes (A-1).

[0040] The average aspect ratio of the single-walled carbon nanotubes (A-3) is preferably 100 to 30,000, more preferably 500 to 20,000, and even more preferably 1,000 to 10,000. When the aspect ratio is 100 or more, the contact resistance between the CNTs is reduced, and electrical conductivity is easily exhibited. Furthermore, when the aspect ratio is 30,000 or less, a dispersion with good fluidity can be obtained. The average aspect ratio of the single-walled carbon nanotubes (A-3) can be obtained by the same method as that for the multi-walled carbon nanotubes (A-1).

[0041] The specific surface area of ​​the single-walled carbon nanotube (A-3) is 100m 2 / g or more is preferable, and 300m 2 / g or more is more preferable, and 400m 2 / g or more is more preferable. 2 / g or less is preferable, and 1000m 2 / g or less is more preferable, and 800m2 / g or less is more preferable. The specific surface area of ​​the single-walled carbon nanotubes (A-3) can be obtained by the same method as that for the multi-walled carbon nanotubes (A-1).

[0042] By setting the average outer diameter, average fiber length, specific surface area and average aspect ratio of the single-walled carbon nanotubes (A-3) within the above ranges, it is possible to achieve high levels of both dispersibility and conductivity, which is preferable.

[0043] The G / D ratio of the single-walled carbon nanotubes (A-3) is preferably 1 or more, more preferably 10 or more, and even more preferably 20 or more. There is no particular upper limit, but it is preferably 1000 or less. The G / D ratio of the single-walled carbon nanotubes (A-3) can be obtained by the same method as that of the multi-walled carbon nanotubes (A-1).

[0044] Commercially available single-walled carbon nanotubes (A-3) include, but are not limited to, ZEONANO SG101 (average outer diameter: 3 to 5 nm) manufactured by Zeon Corporation and TUBALL 01RW02 (average outer diameter: approximately 2 nm) manufactured by OCSiAl.

[0045] The content of the single-walled carbon nanotubes (A-3) is preferably 1 to 100 parts by mass, more preferably 5 to 50 parts by mass, and even more preferably 7 to 40 parts by mass, per 100 parts by mass of the multi-walled carbon nanotubes (A-1). By blending them in this ratio, aggregation of the single-walled carbon nanotubes (A-3) can be suppressed, and both conductivity and transparency can be achieved.

[0046] [Other carbon-based conductive materials other than carbon nanotubes (A')] The carbonaceous conductive material (A') is a carbonaceous conductive material other than carbon nanotubes. Examples of the carbon-based conductive material (A') include carbon materials such as carbon black, fullerene, graphene, multilayer graphene, graphite, etc. Note that graphene and multilayer graphene are flake-, plate-, or scale-like particles, and do not include cylindrical particles. When using a carbonaceous conductive material (A'), it is preferable to use carbon black, which is readily available on the market and has good conductivity and transparency.

[0047] Examples of carbon black include acetylene black, thermal black, furnace black, channel black, lamp black, hollow carbon black, etc. Carbon black obtained by subjecting these carbon blacks to oxidation treatment, graphitization treatment, etc. may also be used.

[0048] The powder resistivity of the carbon-based conductive material (A') is preferably 10 Ω·cm or less. There is no particular lower limit, but it is, for example, 0.001 Ω·cm or more. The powder resistivity of the carbon-based conductive material (A') can be obtained by the same method as that for the multi-walled carbon nanotubes (A-1).

[0049] <Dispersant (B)> The dispersant (B) is a compound capable of dispersing the carbon-based conductive material (A).

[0050] The dispersant is preferably at least one selected from the group consisting of nonionic dispersants, anionic dispersants, cationic dispersants, and amphoteric dispersants, more preferably at least one selected from the group consisting of anionic dispersants, cationic dispersants, and amphoteric dispersants, and even more preferably anionic dispersants.

[0051] The dispersant (B) preferably has an acid value and / or an amine value. The total of the acid value and amine value of the nonvolatile content of the dispersant (B) is preferably 10 mgKOH / g or more and 500 mgKOH / g or less, and more preferably 70 mgKOH / g or more and 200 mgKOH / g or less. The total of the acid value and amine value within the above range is preferred because it provides a dispersing effect, an anti-aggregation effect, and an adsorption stabilizing effect on the carbon-based conductive material.

[0052] The nonvolatile acid value of the dispersant (B) is the acid value (mgKOH / g) determined from the titration amount at the isoelectric point using an automatic potentiometric titrator, and can be measured by the method described in the [Examples] section.

[0053] The nonvolatile amine value of the dispersant (B) is a value obtained by converting the total amine value (mgKOH / g) measured in accordance with the method of ASTM D 2074 into nonvolatile content.

[0054] The dispersant (B) preferably has an acidic group. Examples of the acidic group include a carboxyl group, a sulfo group, and a phosphate group. Among these, a carboxyl group and a phosphate group are preferred, and a carboxyl group is more preferred. Examples of the basic group contained in the dispersant (B) include a primary amino group, a secondary amino group, a tertiary amino group, and a quaternary ammonium base.

[0055] When the dispersant (B) has an acidic group or a basic group, it can be further neutralized with a pH adjuster (D) described below before use. The neutralization of the dispersant (B) may be carried out after dissolving the dispersant (B) in the dispersion medium (C), or may be carried out by adding the pH adjuster (D) while suspending or dispersing the dispersant (B) in the dispersion medium (C).

[0056] Examples of the dispersant (B) include low-molecular-weight dispersants and polymeric dispersants. Among these, polymeric dispersants are preferred, and resin-type dispersants are more preferred. Note that a low-molecular-weight dispersant is a dispersant with a weight-average molecular weight of less than 1,000, and a polymeric dispersant is a dispersant with a weight-average molecular weight of 1,000 or more.

[0057] Among the resin-type dispersants, examples of synthetic resins include (meth)acrylic dispersants, polyurethane dispersants, urethane acrylate dispersants, polyether dispersants, polyester dispersants, polyvinyl alcohol, polyvinyl acetal, polyvinylpyrrolidone, etc. Among these, (meth)acrylic dispersants, urethane acrylate dispersants, and polyether dispersants are preferred, and (meth)acrylic dispersants are more preferred.

[0058] Among the resin-type dispersants, natural resins include, for example, natural polymer compounds such as gum arabic and natural rosin, modified rosin compounds such as hydrogenated rosin and polymerized rosin, and cellulose-based compounds such as hydroxypropyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, and methyl cellulose. Among these, cellulose-based compounds are preferred. In the present invention, resins obtained by modifying natural resins are considered to be natural resins.

[0059] The resin-type dispersant preferably has at least one functional group selected from the group consisting of an aromatic group, a heterocyclic group, and a nitrile group. Examples of the aromatic group include a phenyl group, a naphthyl group, an anthracenyl group, and a phenanthrenyl group. Examples of the heterocyclic group include a pyridyl group, a pyrazinyl group, a pyrimidinyl group, and a pyridazyl group. Among these, a phenyl group, a naphthyl group, a pyridyl group, or a nitrile group is more preferred, and a nitrile group is even more preferred. The presence of these groups strengthens adsorption to the carbon-based conductive material, thereby further improving dispersion stability.

[0060] Commercially available polymer dispersants include Disperbyk-180, 183, 184, 187, 190, 191, 192, 193, 194, 2010, 2013, 2015, 2090, 2091, 2095, and 2096 manufactured by BYK-Chemie; SOLSPERSE-20000, 27000, 41000, 41090, 43000, 44000, 46000, 47000, 53095, and 54000 manufactured by Lubrizol Japan; and Dispex AA4030, AA4040, AA4140, CX4230, CX4231, CX4234, CX4240, CX4320, and Dispex Ultra manufactured by BASF Japan. FA4404, FA4416, FA4425, FA4431, FA4437, FA4480, FA4480, FA4483, PA4550, PA4560, PA4575, PA4585, etc.; Joncryl HPD-196, HPD-96J, PDX-6137A, 63J, 60J, 70J, JDX-6639, JDX-6500, PDX-6102B, etc.; Ajisper PA111, PB711, PB821, PB822, PB824 manufactured by Ajinomoto Fine-Techno Co., Ltd., etc.

[0061] The low molecular weight dispersant may be a nonionic dispersant, an anionic dispersant, a cationic dispersant or an amphoteric dispersant.

[0062] Examples of commercially available low-molecular-weight anionic dispersants include fatty acid salts, alkyl sulfate ester salts, alkylaryl sulfonates, alkylnaphthalenesulfonates, dialkylsulfonates, dialkylsulfosuccinates, alkyldiaryletherdisulfonates, alkylphosphates, polyoxyethylene alkylether sulfates, polyoxyethylene alkylarylether sulfates, naphthalenesulfonate-formalin condensates, and polyoxyethylene alkylphosphate ester salts.

[0063] Examples of commercially available low-molecular-weight nonionic dispersants include polyoxyethylene alkyl ethers, polyoxyethylene alkylaryl ethers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid esters, polyoxyethylene fatty acid esters, polyoxyethylene alkylamines, glycerol borate fatty acid esters, and polyoxyethylene glycerol fatty acid esters.

[0064] Examples of commercially available low molecular weight cationic dispersants include alkylammonium salts, alkylamine salts, and alkylpyridinium salts.

[0065] Examples of commercially available low molecular weight amphoteric dispersants include alkyl betaines, alkyl imidazolinium betaines, alkyl carboxy betaines, and alkyl hydroxy sulfobetaines.

[0066] The weight-average molecular weight of the dispersant (B) is preferably less than 100,000, more preferably 1,000 to 50,000, even more preferably 2,000 to 30,000, and even more preferably 5,000 to 20,000. Having an appropriate weight-average molecular weight improves the adsorption to the carbon-based conductive material, and further improves the dispersion stability of the conductive material dispersion. The weight-average molecular weight is a weight-average molecular weight calculated in terms of standard polystyrene obtained by gel permeation chromatography (GPC) measurement, and can be measured by the method described in the [Examples] section.

[0067] The amount of dispersant (B) blended per 100 parts by mass of carbonaceous conductive material (A) is preferably 1 to 1500 parts by mass, more preferably 100 to 1000 parts by mass, even more preferably 100 to 500 parts by mass, and still more preferably 100 to 300 parts by mass.

[0068] [(Meth)acrylic dispersants] The dispersant (B) may contain a (meth)acrylic dispersant (resin-type anionic dispersant) containing a structural unit derived from a carboxyl group-containing monomer. The carboxyl group is preferably neutralized with a pH adjuster (D) before use. Furthermore, it is particularly preferable that the dispersant (B) further contains a structural unit derived from a nitrile group-containing monomer.

[0069] Examples of the carboxyl group-containing monomer include (meth)acrylic acid, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxypropyl phthalate, 2-(meth)acryloyloxyethyl hexahydrophthalate, 2-(meth)acryloyloxypropyl hexahydrophthalate, ethylene oxide-modified succinic acid (meth)acrylate, and carboxyl group-containing (meth)acrylate such as β-carboxyethyl (meth)acrylate. Among these, (meth)acrylic acid is preferably used.

[0070] The nitrile group-containing monomer may, for example, be (meth)acrylonitrile, and it is preferable to use acrylonitrile.

[0071] The content of structural units derived from carboxyl group-containing monomers in 100% by mass of the (meth)acrylic dispersant is preferably 1 to 50% by mass, more preferably 5% by mass or more, even more preferably 10% by mass or more, and particularly preferably 20% by mass or more, and more preferably 40% by mass or less, even more preferably 30% by mass or less. By setting the amount of the structural unit derived from the carboxyl group-containing monomer in this manner, it is possible to improve the affinity for the solvent while maintaining the dispersibility of the carbon-based conductive material (A).

[0072] The content of structural units derived from nitrile group-containing monomers in 100% by mass of the (meth)acrylic dispersant is preferably 10 to 99% by mass, more preferably 30% by mass or more, even more preferably 60% by mass or more, and particularly preferably 70% by mass or more, and more preferably 95% by mass or less, even more preferably 90% by mass or less, and particularly preferably 80% by mass or less. When an appropriate amount of structural units derived from a nitrile group-containing monomer is contained, the dispersibility of the carbon-based conductive material (A) can be further improved while maintaining affinity to the solvent.

[0073] The (meth)acrylic dispersant may be used after partially modifying the carboxyl group or nitrile group. The (meth)acrylic dispersant may also contain structural units derived from monomers having a (meth)acryloyl group or structural units derived from monomers having a polymerizable unsaturated group other than a (meth)acryloyl group. Examples of the polymerizable unsaturated group other than a (meth)acryloyl group include a vinyl group and a (meth)allyl group.

[0074] Other examples of monomers having a (meth)acryloyl group include (meth)acrylic acid esters. Examples of (meth)acrylic acid esters include (meth)acrylic acid esters containing a chain aliphatic alkyl group such as methyl (meth)acrylate and ethyl (meth)acrylate; (meth)acrylic acid esters containing a branched aliphatic alkyl group such as 2-ethylhexyl (meth)acrylate and isostearyl (meth)acrylate; (meth)acrylic acid esters containing a cyclic aliphatic alkyl group such as cyclohexyl (meth)acrylate and isobornyl (meth)acrylate; (meth)acrylic acid alkyl esters substituted with an alicyclic epoxy group such as glycidyl (meth)acrylate and (3-ethyloxetan-3-yl)methyl (meth)acrylate; and (meth)acrylic acid alkyl esters substituted with an alkylene glycol monoalkyl ether group such as 2-methoxyethyl (meth)acrylate and polyethylene glycol monomethyl ether (meth)acrylate.

[0075] Examples of the monomer having an aromatic group include styrenes such as styrene and α-methylstyrene; Aromatic group-substituted (meth)acrylic acid alkyl esters such as benzyl (meth)acrylate and phenoxyethyl (meth)acrylate; Monomers having an anthracenyl group, such as vinylanthracene and 9-anthryl (meth)acrylate; Monomers having a naphthyl group, such as vinylnaphthalene and 1-naphthyl (meth)acrylate; Monomers having a phenanthrenyl group, such as vinylphenanthrene and (9-phenanthryl)methyl (meth)acrylate; etc.

[0076] Examples of the monomer having a heterocyclic group include monomers having a pyridyl group such as vinylpyridine and pyridine(meth)acrylate; monomers having a pyridazyl group such as vinylpyridazine and pyridazine(meth)acrylate; monomers having a pyrimidinyl group such as vinylpyrimidine and pyrimidine(meth)acrylate; and monomers having a pyrazinyl group such as vinylpyrazine and pyrazine(meth)acrylate.

[0077] Examples of methods for synthesizing the (meth)acrylic dispersant include solution polymerization, suspension polymerization, bulk polymerization, emulsion polymerization, and precipitation polymerization, with solution polymerization and precipitation polymerization being preferred. Examples of polymerization reaction systems include addition polymerization such as ionic polymerization, free radical polymerization, and living radical polymerization, with free radical polymerization being preferred. Examples of the radical polymerization initiator include peroxides, azo-based initiators, etc. Furthermore, when polymerizing the dispersant, a molecular weight modifier such as a chain transfer agent can be used.

[0078] Examples of chain transfer agents include alkyl mercaptans such as octyl mercaptan, nonyl mercaptan, decyl mercaptan, dodecyl mercaptan, and 3-mercapto-1,2-propanediol, thioglycolic acid esters such as octyl thioglycolate, nonyl thioglycolate, and 2-ethylhexyl thioglycolate, 2,4-diphenyl-4-methyl-1-pentene, 1-methyl-4-isopropylidene-1-cyclohexene, α-pinene, and β-pinene. In particular, 3-mercapto-1,2-propanediol, thioglycolic acid esters, 2,4-diphenyl-4-methyl-1-pentene, 1-methyl-4-isopropylidene-1-cyclohexene, α-pinene, and β-pinene are preferred because the resulting polymer has a low odor.

[0079] The amount of the chain transfer agent used is preferably 0.01 to 4 parts by mass, more preferably 0.1 to 2 parts by mass, relative to 100 parts by mass of the total of all monomers. By adjusting the amount of the chain transfer agent within the above range, the weight average molecular weight of the (meth)acrylic dispersant can be adjusted to a suitable range.

[0080] <Dispersion medium (C)> Examples of the dispersion medium (C) include water and organic solvents. The content of water in 100% by mass of the dispersion medium (C) is preferably 20% by mass or more, more preferably 50% by mass or more, even more preferably 80% by mass or more, and particularly preferably 100% by mass.

[0081] The organic solvent is preferably a water-soluble solvent.

[0082] Water-soluble solvents include alcohols (methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, benzyl alcohol, etc.), polyhydric alcohols (ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol, etc.), polyhydric alcohol ethers (ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether, propylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ...methyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, ethylene glycol monophenyl ether, propylene glycol monophenyl ether, etc.), amines (ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine, etc.), amides (N-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone (NEP), N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N-methylcaprolactam, etc.), heterocyclics (cyclohexylpyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, γ-butyrolactone, etc.), sulfoxide-based (dimethyl sulfoxide, etc.), sulfone-based (hexamethylphosphoramide, sulfolane, etc.), lower ketone-based (acetone, methyl ethyl ketone, etc.), and others, such as tetrahydrofuran, acetonitrile, etc.

[0083] <pH adjuster (D)> The pH adjuster (D) is a compound that neutralizes the functional groups of the dispersant (B). Depending on the functional groups of the dispersant (B), a basic compound or an acidic compound is used as the pH adjuster (D).

[0084] The basic compound is preferably an inorganic base, more preferably a hydroxide of an alkali metal, and even more preferably sodium hydroxide or potassium hydroxide. By using these basic compounds, the acidic groups of the dispersant (B) can be effectively neutralized, and a good dispersant function can be exhibited.

[0085] The calculation of the blending amount of the dispersant (B) is calculated by regarding the total amount of the mass of the dispersant (B) before neutralization and the mass of the pH adjuster (D) as the mass of the dispersant (B).

[0086] The amount of the basic compound used is preferably 1 equivalent or more, more preferably 1.5 equivalents or more, and even more preferably 2 equivalents or more, based on the acidic groups of the dispersant (B). Also, it is preferably 10 equivalents or less, more preferably 7 equivalents or less, and even more preferably 5 equivalents or less.

[0087] The acidic compound is preferably acetic acid or an inorganic acid. Examples of the inorganic acid include hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, carbonic acid, etc.

[0088] The amount of the acidic compound used is preferably 1 equivalent or more, more preferably 1.5 equivalents or more, and even more preferably 2 equivalents or more, based on the acidic groups of the dispersant (B). Also, it is preferably 8 equivalents or less, more preferably 6 equivalents or less, and even more preferably 4 equivalents or less.

[0089] <Resin (E)> Resin (E) is a binder resin, and examples thereof include natural resins and synthetic resins. The weight-average molecular weight of resin (E) is preferably 100,000 or more, more preferably 200,000 or more, and particularly preferably 300,000 or more. Also, it is preferably 10,000,000 or less, more preferably 5,000,000 or less, and particularly preferably 1,000,000 or less.

[0090] Examples of the resin (E) include acrylic resins, polyester resins, polyurethane resins, epoxy resins, phenoxy resins, polyamide resins, polyether resins, silicone resins, polyolefin resins, polystyrene-based resins, polyvinyl alcohol-based resins, polyvinyl ester-based resins, polyvinylpyrrolidone-based resins, vinyl chloride-based resins, carbonate-based resins, unsaturated carboxylic acid-based resins, fluorine-based resins, celluloses, rosins, and natural rubber, as well as copolymers thereof. Among these, acrylic resins, polyester resins, polyurethane resins, and polyolefin resins are preferred, and acrylic resins are more preferred.

[0091] The resin (E) can be an emulsion of a binder resin. The average primary particle size of the emulsion is preferably 10 nm or more, more preferably 50 nm or more, and even more preferably 100 nm or more. The average primary particle size is preferably 10 μm or less, more preferably 1 μm or less, and even more preferably 500 nm or less. The average primary particle size of the resin (E) is the number average value of the primary particle sizes measured by randomly selecting approximately 20 particles of the resin (E) from an enlarged image taken with a scanning electron microscope.

[0092] When the resin (E) has a reactive functional group such as a polymerizable unsaturated group or an epoxy group, curability is obtained. When the resin (E) is a curable resin, it is preferably a thermosetting resin or a photocurable resin, and more preferably a thermosetting resin.

[0093] <Non-conductive particles (F)> The non-conductive particles (F) are insulating particles.

[0094] Examples of the non-conductive particles (F) include pigments, aluminum oxide, silica, amorphous silica, crystalline silica, magnesium hydroxide, calcium oxide, magnesium oxide, and barium titanate.

[0095] Examples of pigments include extender pigments, white pigments, black pigments, chromatic pigments, and anti-rust pigments, and any of these can be selected as required.

[0096] Examples of extender pigments include calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, barium sulfate, aluminum hydroxide, talc, mica, and kaolin.

[0097] Examples of white pigments include titanium oxide and zinc oxide.

[0098] Examples of black pigments include black iron oxide.

[0099] Examples of chromatic pigments include diketopyrrolopyrrole pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, perinone pigments, perylene pigments, thiazine indigo pigments, triazine pigments, benzimidazolone pigments, indole pigments such as benzoisoindole, isoindoline pigments, isoindolinone pigments, quinophthalone pigments, naphthol pigments, phthalocyanine pigments, threne pigments, metal complex pigments, and azo pigments such as azo, disazo, and polyazo.

[0100] The non-conductive particles (F) preferably have a powder resistivity of 100 Ω·cm or more. The powder resistivity of the non-conductive particles (F) can be obtained by the same method as that for the multi-walled carbon nanotubes (A-1).

[0101] The non-conductive particles (F) preferably have a primary particle size of 10 nm to 100 μm, more preferably 50 nm to 10 μm, even more preferably 100 nm to 5 μm, and particularly preferably 200 nm to 2 μm.

[0102] The shape of the non-conductive particles (F) is not particularly limited, and examples thereof include spherical, plate-like, needle-like, fibrous, circular, cubic, scaly, flake-like, etc. Among these, spherical shapes are preferred from the viewpoints of ease of uniform mixing with the dispersion liquid or resin and of less aggregation.

[0103] <Neutralizer (G)> The pH of the conductive material dispersion of the present invention can be adjusted as needed using a neutralizer (G). The neutralizer (G) may be a basic compound or an acidic compound, and may be used alone or in combination of two or more kinds. The neutralizing agent (G) is a different compound having the opposite polarity to the pH adjuster (D). In other words, when an acidic compound is used as the pH adjuster (D), the neutralizing agent (D) is a basic compound, and when a basic compound is used as the pH adjuster (D), the neutralizing agent (D) is an acidic compound.

[0104] The acidic compound is not particularly limited, and inorganic acids or organic acids can be used. From the viewpoint of industrial ease of handling, such as corrosiveness and safety, it is preferable to use organic acids.

[0105] Examples of the organic acid include organic compounds having a carboxyl group, organic compounds having a phosphate group, organic compounds having a sulfo group, etc. Among these, it is preferable to use a compound having a carboxyl group.

[0106] Examples of organic compounds having a carboxyl group include acetic acid, formic acid, propionic acid, butyric acid, valeric acid, and oxalic acid, and it is preferable to use acetic acid.

[0107] Examples of inorganic acids include hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid.

[0108] The basic compound is not particularly limited, but an inorganic base or an organic base can be used, and it is preferable to use an inorganic base.

[0109] Examples of inorganic bases include ammonia, chlorides, hydroxides, carbonates, nitrates, sulfates, phosphates, tungstates, vanadates, molybdates, niobates, and borates of alkali metals or alkaline earth metals. Among these, from the viewpoints of commercial availability and ease of handling, it is preferable to use chlorides, hydroxides, or carbonates of alkali metals or alkaline earth metals, and it is more preferable to use hydroxides of alkali metals.

[0110] Examples of alkali metal hydroxides include lithium hydroxide, sodium hydroxide, and potassium hydroxide, with sodium hydroxide or potassium hydroxide being more preferred. Examples of alkali metal carbonates include lithium carbonate, sodium carbonate, sodium hydrogen carbonate, potassium carbonate, and potassium hydrogen carbonate.

[0111] Examples of the organic base include primary, secondary, tertiary, or quaternary alkylamines having an optionally substituted alkyl group having 1 to 40 carbon atoms, and other organic bases. The optionally substituted alkyl group preferably has 1 to 10 carbon atoms, and more preferably 1 to 5 carbon atoms. The term "optionally substituted alkyl group" means that a hydrogen atom of the alkyl group may be substituted, and examples of the substituent include a hydroxy group.

[0112] Examples of primary alkylamines having an optionally substituted alkyl group having 1 to 40 carbon atoms include methylamine, ethylamine, propylamine, butylamine, isobutylamine, 2-ethylhexylamine, laurylamine, stearylamine, oleylamine, 2-aminoethanol, 3-aminopropanol, 3-ethoxypropylamine, and monoethanolamine. Furthermore, examples of secondary alkylamines having an optionally substituted alkyl group having 1 to 40 carbon atoms include dimethylamine, diethylamine, dipropylamine, and 2-methylaminoethanol. Furthermore, examples of tertiary alkylamines having an optionally substituted alkyl group having 1 to 40 carbon atoms include trimethylamine, triethylamine, tri-n-butylamine, dimethylbenzylamine, and 2-(dimethylamino)ethanol. Furthermore, examples of quaternary alkylamines having an alkyl group having 1 to 40 carbon atoms which may be substituted include tetramethylammonium hydroxide, tetraethylammonium hydroxide, and trimethyl(2-hydroxyethyl)ammonium hydroxide.

[0113] Other organic bases that may be used include compounds containing a basic nitrogen atom, such as 1,8-diazabicyclo[5.4.0]undecene-7 (DBU), 1,5-diazabicyclo[4.3.0]nonene-5 (DBN), 1,4-diazabicyclo[2.2.2]octane (DABCO), imidazole, and 1-methylimidazole.

[0114] The neutralizing agent (G) consumed by the neutralization forms a neutralized salt, which can remain and be contained in the conductive material dispersion or conductive film.

[0115] <Other additives> The conductive material dispersion may contain other additives such as dye derivatives, antifoaming agents, leveling agents, rheology control agents, anti-settling agents, curing catalysts, antioxidants, ultraviolet absorbers, and surface conditioners. Other additives can be added at any time and by any method.

[0116] [Dye derivatives] The dye derivative is a compound having an acidic group, a basic group, a neutral group, etc. in an organic dye residue. Examples of the dye derivative include compounds having an acidic substituent such as a sulfo group, a carboxyl group, or a phosphate group, and amine salts thereof; compounds having a basic substituent such as a sulfonamide group or a terminal tertiary amino group; and compounds having a neutral substituent such as a phenyl group or a phthalimidoalkyl group. Examples of organic pigments include diketopyrrolopyrrole pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, perinone pigments, perylene pigments, thiazine indigo pigments, triazine pigments, benzimidazolone pigments, indole pigments such as benzoisoindole, isoindoline pigments, isoindolinone pigments, quinophthalone pigments, naphthol pigments, phthalocyanine pigments, threne pigments, metal complex pigments, and azo pigments such as azo, disazo, and polyazo.

[0117] [Antifoaming agent] Any known defoaming agent can be used. It is not limited to commercially available defoaming agents, but any agent that has a defoaming effect, such as a wetting agent, a hydrophilic organic solvent, or a water-soluble organic solvent, can be used. The defoaming agents can be used alone or in combination of two or more.

[0118] Examples of the defoaming agent include alcohols such as ethanol, propanol, isopropanol, butanol, octyl alcohol, hexadecyl alcohol, acetylene alcohol, ethylene glycol monobutyl ether, methyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, acetylene glycol, polyoxyalkylene glycol, propylene glycol, and other glycols. Fatty acid esters: diethylene glycol laurate, glycerin monoricinoleate, alkenyl succinic acid derivatives, sorbitol monolaurate, sorbitol trioleate, polyoxyethylene monolaurate, polyoxyethylene sorbitol monolaurate, natural waxes, etc. Amide-based: polyoxyalkylene amide, acrylate polyamine, etc. Phosphate esters: tributyl phosphate, sodium octyl phosphate, etc. Metal soaps: aluminum stearate, calcium oleate, etc. Oils and fats: animal and vegetable oils, sesame oil, castor oil, etc. Mineral oils: kerosene, paraffin, etc. Silicone-based: dimethyl silicone oil, silicone paste, silicone emulsion, organic modified polysiloxane, fluorosilicone oil, etc.

[0119] <Conductive material dispersion liquid> The conductive material dispersion of the present invention contains a carbon-based conductive material (A), a dispersant (B) and a dispersion medium (C), wherein the carbon-based conductive material (A) contains multi-walled carbon nanotubes (A-1), and the iron content in the multi-walled carbon nanotubes (A-1) is greater than 0 mass% and not more than 5 mass%, and the total content of cobalt and molybdenum is 0 mass% or more and not more than 0.1 mass%.

[0120] The conductive material dispersion of the present invention contains multi-walled carbon nanotubes (A-1) (hereinafter referred to as multi-walled CNTs (A-1)), which allows the formation of a conductive film that is both transparent and conductive. Because the multi-walled CNTs (A-1) have a branched structure, the CNTs come into contact with each other during the formation of the conductive film, forming a three-dimensional conductive network. This allows the desired conductivity to be obtained with a smaller amount than conventionally, making it possible to form a conductive film that is both transparent and conductive. Multi-walled CNTs (A-1) can be produced using iron as a catalyst without using cobalt or molybdenum during production. Because multi-walled CNTs (A-1) have a highly branched structure, they can achieve a three-dimensional conductive network even when branched chains are broken during the dispersion process when producing a conductive material dispersion. However, since there is no parameter that indicates the degree of branching of multi-walled CNTs (A-1), in this specification, the highly branched structure is expressed as the content of the production catalyst for multi-walled CNTs (A-1).

[0121] The content of the carbonaceous conductive material (A) in 100% by mass of the nonvolatile content in the dispersion is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 3% by mass or less, and even more preferably 2% by mass or less, and is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more.

[0122] The content of the multi-walled carbon nanotubes (A-1) in the conductive material dispersion is preferably 0.01 to 15 mass %, more preferably 0.1 to 5 mass %, and even more preferably 0.2 to 1 mass %. By keeping the content of the multi-walled carbon nanotubes (A-1) within this range, the occurrence of sediment or agglomerates is suppressed, and the dispersion state becomes uniform and good, which is preferable.

[0123] When multi-walled carbon nanotubes (A-2) are used, the content of the multi-walled carbon nanotubes (A-2) in the conductive material dispersion is preferably 0.01 to 7.5 mass %, more preferably 2.5 mass % or less, and even more preferably 0.5 mass % or less. By setting the content to the above range, it is possible to achieve both dispersion stability and conductivity without inhibiting the conductive network of the multi-walled carbon nanotubes (A-1), which is preferable.

[0124] When single-walled carbon nanotubes (A-3) are used, the content of the single-walled carbon nanotubes (A-3) in the conductive material dispersion is preferably 0.01 to 7.5 mass%, more preferably 2.5 mass% or less, and even more preferably 0.5 mass% or less. By setting the content within the above range, it is possible to achieve high levels of both dispersion stability and conductivity without inhibiting the conductive network of the multi-walled carbon nanotubes (A-1).

[0125] When resin (E) is used in the conductive material dispersion, the content of dispersant (B) relative to 100 parts by mass of resin (E) is preferably 0.001 parts by mass or more and 4 parts by mass or less, and more preferably 0.01 parts by mass or more and 2 parts by mass or less.

[0126] The content of the non-conductive particles (F) is preferably 1% by mass or more and 70% by mass or less, more preferably 1% by mass or more and 65% by mass or less, and even more preferably 1% by mass or more and 60% by mass or less, based on 100% by mass of the conductive material dispersion.

[0127] In one embodiment, in a conductive dispersion liquid containing a resin (E) and non-conductive particles (F), the content of the resin (E) in 100% by mass of the non-volatile content of the conductive dispersion liquid is preferably 1% by mass or more and 99.9% by mass or less, more preferably 5% by mass or more and 90% by mass or less, and even more preferably 10% by mass or more and 80% by mass or less.

[0128] The content of the antifoaming agent in the conductive material dispersion is preferably 0.01 to 1 mass %, more preferably 0.01 to 0.5 mass %, and even more preferably 0.05 to 0.2 mass %. By keeping the content of the antifoaming agent within this range, good antifoaming properties can be obtained.

[0129] The viscosity of the conductive material dispersion liquid is such that the TI value calculated by the following formula (1) is preferably 2 or more, more preferably 2.5 or more, and even more preferably 3 or more. The TI value is preferably 10 or less, more preferably 7 or less, and even more preferably 5 or less. Equation (1) TI value = (viscosity measured at 6 rpm / viscosity measured at 60 rpm) The viscosity of the conductive material dispersion can be determined by the method described in the Examples. By setting the TI value within this range, the dispersion is less likely to separate or settle, and a dispersion with good storage stability can be obtained.

[0130] The 50% particle size (D50) of the conductive material dispersion is preferably 10 μm or more and 150 μm or less, more preferably 20 μm or more and 140 μm or less, and even more preferably 30 μm or more and 130 μm or less. By keeping it within this range, it is possible to achieve a high level of compatibility between the viscosity and TI value of the dispersion and the conductivity of the formed conductive film. The 50% particle size (D50) of the conductive material dispersion can be measured using a laser diffraction particle size distribution analyzer (Microtrac MT3000II, manufactured by Microtrac-Bell) using the following method. First, 0.5 g of the conductive material dispersion is diluted with 30 g of water and then treated with an ultrasonic homogenizer (output 100 W) for 5 minutes to prepare a measurement sample. Next, 1 to 10 drops of the measurement sample are poured into a measurement cell and diluted with a sufficient amount of water. The particle size distribution is measured at 25°C and analyzed with a particle refractive index of 1.746 and a solvent refractive index of 1.33. The particle size corresponding to 50% of the cumulative value (volume basis) in the obtained particle size distribution is defined as the 50% particle size (D50).

[0131] The surface resistivity (R1) of the conductive dispersion coating is 1.0 x 10 5 Ω / □ or less is preferable, 1.0×10 4 Ω / □ or less is more preferable, and 1.0×10 3 The lower the surface resistivity (R1) of the coating film, the better, so there is no particular lower limit. -2 It is Ω / □ or more. The surface resistivity (R1) of the coating film was measured using a Loresta-GX MCP-T700 (manufactured by Mitsubishi Chemical Analytech Co., Ltd., four-terminal method) on a coating film prepared by applying the conductive material dispersion onto a polyethylene terephthalate (PET) film using a 7-mil applicator, leveling at 20°C for 10 minutes, and then drying at 100°C for 20 minutes.

[0132] The lightness (L1) of the coating film of the conductive material dispersion is preferably 25 or less, more preferably 23 or less, and even more preferably 20 or less. The lightness is preferably 0 or more, more preferably 3 or more, and even more preferably 5 or more. The chromaticity b value (b1) of the coating film of the conductive material dispersion is preferably 3 or less, more preferably 2 or less, and even more preferably 1 or less. The chromaticity b value is preferably -10 or more, more preferably -5 or more, and even more preferably -3 or more. Although the reason for this is not clear, it has been found that when the brightness and b value of the coating film satisfy the above numerical ranges, the carbon-based conductive material (A) can be dispersed in a state where a particularly high degree of conductivity and transparency can be achieved at the same time. The lightness (L1) and b value (b1) of the coating film can be obtained by the method described in the examples.

[0133] The dispersion may further contain a resin (E) or non-conductive particles (F). The dispersion may be suitably used in applications requiring electrical conductivity, and more suitably used as a conductive paint. Examples of conductive paints include antistatic paints, transparent conductive paints, and electrode paints. Among these, the dispersion is preferably used as an antistatic paint or transparent conductive paint due to its excellent transparency.

[0134] <Production of Conductive Material Dispersion> In the conductive material dispersion of the present invention, a carbon-based conductive material (A) containing multi-walled carbon nanotubes (A-1) is dispersed in a dispersion medium (C) using a dispersant (B). In this case, the dispersant (B) and the carbon-based conductive material (A) are added simultaneously or sequentially and mixed, thereby dispersing the carbon-based conductive material (A) while allowing the dispersant (B) to act on (adsorb) the carbon-based conductive material (A). From the viewpoint of workability, it is preferable to dissolve, swell or disperse the dispersant (B) in water, and then add and mix the carbon-based conductive material (A) to cause the dispersant (B) to act on (adsorb) the carbon-based conductive material (A).

[0135] The dispersing device is not particularly limited, and any conventionally known dispersing device can be used, for example, a rotor-stator type dispersing device such as a colloid mill (PUC Colloid Mill manufactured by PUC, Colloid Mill MK manufactured by IKA), a homogenizer (Clearmix manufactured by M Technique, Filmix manufactured by PRIMIX, Abramix manufactured by Silverson, etc.), a cone mill (Cone Mill MKO manufactured by IKA, etc.), Ultrasonic dispersers such as Hielscher UP200St, High-pressure homogenizers such as wet jet mills (such as Genus PY manufactured by Genus, Starburst manufactured by Sugino Machine, and Nanomizer manufactured by Nanomizer), Mixers such as dispersers, homo mixers, planetary mixers, etc. Examples of media-type dispersers include a paint conditioner (manufactured by Red Devil), a ball mill, a sand mill (such as "Dyno Mill" manufactured by Shinmaru Enterprises), an attritor, a pearl mill (such as "DCP Mill" manufactured by Eirich), and a Co-ball mill. Among these, at least one media-less disperser selected from the group consisting of a rotor-stator type disperser, an ultrasonic disperser, and a high-pressure homogenizer is preferred, a rotor-stator type disperser or a high-pressure homogenizer is more preferred, and a high-pressure homogenizer is even more preferred. Among high-pressure homogenizers, it is more preferable to use a disperser equipped with a mechanism for dispersing by the impact force of cavitation. An example of such a disperser is the "Single Nozzle Chamber" model of "Starburst" manufactured by Sugino Machine Ltd.

[0136] In one embodiment using a high-pressure homogenizer that performs dispersion treatment using the impact force of cavitation, the mixed liquid to be dispersed is preferably dispersed by pass dispersion at a spray pressure of 50 MPa to 150 MPa. By setting the dispersion treatment conditions in this way, the multi-walled carbon nanotubes (A-1) can be uniformly dispersed without excessively damaging their structure, and particularly good conductivity can be obtained. In this invention, "pass dispersion" refers to a method in which the entire amount of sample liquid is sequentially supplied to the dispersion section of a disperser to perform dispersion processing, and "one-pass dispersion" refers to the entire amount of sample liquid passing through the dispersion section of a disperser once. By employing this process, the entire sample liquid reliably passes through the dispersion section of the disperser, enabling uniform processing.

[0137] One embodiment of the method for producing the conductive material dispersion preferably includes the following steps. First, a mixed solution containing a carbon-based conductive material (A), a dispersant (B), and a dispersion medium (C) is prepared, and the pH is adjusted to 7.0 or higher to make it basic. When a polymer dispersant containing a carboxyl group-containing monomer unit is used as the dispersant (B), the pH can be adjusted to 7.5 or higher by sufficiently neutralizing the carboxyl group with a pH adjuster (D). Next, this mixture is dispersed using a rotor-stator type disperser. For example, using a magic LAB (manufactured by IKA), the clearance between the rotor and stator is set to 318 μm, and the entire mixture is passed through the rotor (IKA Ident No. U080674) and stator (IKA Ident No. U083555) once (single-pass dispersion), after which circulation dispersion is performed with the dispersion treatment time set to 15 minutes per 1 kg of mixture to obtain a preliminary dispersion. Thereafter, a dispersion process is further carried out using a high-pressure homogenizer. For example, a Starburst Lab (manufactured by Sugino Machine Co., Ltd.) equipped with a single nozzle chamber is used, with a nozzle diameter of 0.2 mm, a spray pressure of 100 MPa, and a discharge rate of 700 g / min, and the entire amount of the preliminary dispersion is subjected to 10 pass dispersion processes to obtain a conductive material dispersion.

[0138] The conductive material dispersion liquid is preferably produced by the following steps (a) and (b). [Process (a)] A process in which a carbon-based conductive material (A), a dispersant (B), and a dispersion medium (C) are mixed to prepare a mixed liquid, and then the mixed liquid is dispersed at a pH of 7 or higher.

[0139] [Step (b)] After step (a), a step of adjusting the pH to be between 6 and 13.

[0140] First, step (a) will be described in detail. The carbon-based conductive material (A) and the dispersant (B) may each have an acidic or basic functional group. In step (a), good dispersibility can be obtained by mixing the carbon-based conductive material (A), the dispersant (B), and the dispersion medium (C), and then adjusting the pH to 7 or higher and performing a dispersion treatment. The pH in this step is preferably 7.5 to 14, more preferably 8 to 14, and even more preferably 9 to 13.5. Although the mechanism of action is unclear, it is speculated that by adjusting the pH in advance during the dispersion treatment process, it is possible to eliminate the effects on pH caused by, for example, the carbon-based conductive material (A) or the dispersant (B), while also stably controlling the solubility and adsorption of the dispersant (B), thereby achieving good dispersibility.

[0141] In step (a), it is preferable to use an anionic or amphoteric polymer dispersant containing a carboxyl group-containing monomer unit as the dispersant (B). When using such a polymer dispersant, the pH can be adjusted to 7 or higher using a pH adjuster (D).

[0142] Next, step (b) will be described in detail. In step (a), dispersion treatment is carried out in a neutral to basic environment. However, if the pH is high, problems may arise, such as corrosiveness when the dispersion is stored in a container, safety during handling, and precipitation of resin (E) when resin (E) is added. Therefore, in step (b), a neutralizer (G) is further added to adjust the pH to 6 to 13. The pH after adjustment is preferably 6 to 12, more preferably 7 to 12, and even more preferably 8 to 11. Furthermore, the pH in step (b) is preferably lower by 1 or more than that in step (a). In the present invention, even after adjusting the pH to fall within the above range, the dispersibility and storage stability of the dispersion are not impaired, and a conductive material dispersion that is easy to handle can be obtained.

[0143] The pH values ​​in steps (a) and (b) are values ​​measured using a pH meter at a liquid temperature of 25° C. The pH can be measured using, for example, a pH detector for chemical processes, such as a PH4C manufactured by Yokogawa Electric Corporation.

[0144] <Conductive film> The conductive film of the present invention contains a carbon-based conductive material (A), a dispersant (B), and a resin (E). The carbon-based conductive material (A) contains multi-walled carbon nanotubes (A-1). If necessary, non-conductive particles (F) may be blended. The conductive film of the present invention can be obtained, for example, by applying the conductive dispersion of the present invention to a substrate and drying and / or curing the coating.

[0145] The content of the carbonaceous conductive material (A) in 100% by mass of the conductive film is preferably 0.002% by mass or more and 4% by mass or less, and more preferably 0.01% by mass or more and 2% by mass or less.

[0146] The content of the multi-walled carbon nanotubes (A-1) in 100% by mass of the conductive film is preferably 0.001% by mass or more and 2% by mass or less, and more preferably 0.005% by mass or more and 1% by mass or less.

[0147] In the conductive film, the content of the dispersant (B) relative to 100 parts by mass of the resin (E) is preferably 0.001 parts by mass or more and 4 parts by mass or less, more preferably 0.01 parts by mass or more and 2 parts by mass or less.

[0148] In 100% by mass of the conductive film, the total content of the dispersant (B) and the resin (E) is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, and even more preferably 50% by mass or more, and is preferably 99.9% by mass or less, more preferably 90% by mass or less.

[0149] The thickness of the conductive film is preferably 0.01 μm or more and 100 μm or less, and more preferably 0.1 μm or more and 50 μm or less.

[0150] The conductivity of the conductive film is 1.0 x 10 -4 mS / cm or more is preferable, and 1.0 × 10 -2 It is more preferably mS / cm or more, and even more preferably 1 mS / cm or more.

[0151] When forming a conductive film by coating a conductive dispersion, the coating can be performed by various known methods, such as die coating, dip coating, roll coating, doctor coating, gravure coating, screen printing, brush coating, roller coating, and spray coating. After coating, the film can be dried using a dryer. Examples of the dryer include room temperature dryers, blower dryers, warm air dryers, infrared heaters, and far-infrared heaters.

[0152] When a curable resin is used as the resin (E), the curing method is not particularly limited, but examples thereof include aging at room temperature or at elevated temperature. The aging period for the curing reaction is, for example, about 1 to 5 days at 40°C, or about 2 to 10 hours at 180°C. If necessary, the curing reaction can be carried out in multiple temperature steps.

[0153] <Base material> The conductive material dispersion of the present invention can be applied to various conventionally known substrates. Examples of the substrate include metal substrates such as iron, stainless steel, and aluminum; cement-based substrates such as cement and gypsum; and plastic substrates such as polyvinyl chlorides, polyesters, polycarbonates, and acrylics. These substrates may be surface-treated.

[0154] The substrate may have various shapes, such as a sheet, a film, or a plate. These substrates may be used in a flat or curved state. If necessary, they may be subjected to a roughening treatment or a smoothing treatment to adjust the roughness of the coating surface. [Example]

[0155] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to these examples. In these examples, parts represent parts by mass, and % represents % by mass. Carbon nanotubes may also be referred to as "CNTs."

[0156] In the present examples and comparative examples, the following materials were used in producing the conductive material dispersion liquid: The carbon nanotubes used in the examples and comparative examples contained the metal components shown in Table 1.

[0157] <Carbon-based conductive material> [Multi-walled carbon nanotubes (A-1)] ATHLOS: ATHLOS SR1200 (multi-walled carbon nanotubes manufactured by Cabot Corporation, average outer diameter: 13 nm, specific surface area: 210 m 2 / g, average aspect ratio 500) CNT-2: Prepared by the following method. 15 parts of ATHLOS SR1200 were weighed into a glass container, and 800 parts of 15% hydrochloric acid was added, followed by thorough stirring using a stirrer. The mixture was then thoroughly diluted with purified water and filtered using a membrane filter. After thoroughly rinsing the hydrochloric acid with purified water, the mixture was dried at 60°C for 12 hours to obtain CNT-2. Average outer diameter: 13 nm, specific surface area: 210 m 2 / g, average aspect ratio 500. CNT-3: Multi-walled carbon nanotube, average outer diameter: 12 nm, specific surface area: 250 m 2 / g, average aspect ratio 700.

[0158] [Multi-walled carbon nanotubes (A-2)] 6A: JENOTUBE6A (JEIO, multi-walled carbon nanotube, average outer diameter: 6 nm, specific surface area: 700 m 2 / g, average aspect ratio 9700) 100T: K-Nanos 100T (Kumho Petrochemical Co., Ltd., multi-walled carbon nanotubes, average outer diameter: 13 nm, specific surface area: 240 m 2 / g, average aspect ratio 2600)

[0159] [Single-walled carbon nanotubes (A-3)] TUBALL 01RW02: OCSIAL, single-walled carbon nanotubes, average outer diameter: 1.5 nm, specific surface area: 490 m 2 / g, average aspect ratio 3000.

[0160] [Carbon-based conductive material (A')] ·Li-400: DENKA BLACK Li-400 (manufactured by Denka, primary particle diameter 48 nm, specific surface area 39 m 2 / g).

[0161] <Dispersant (B)> Copolymer B-1: (Meth)acrylic dispersant with nitrile groups, resin-type dispersant. Weight average molecular weight: 25,000, acid value: 175 mg KOH / g, non-volatile content: 100%. Copolymer B-2: (Meth)acrylic dispersant with nitrile groups, resin-type dispersant. Weight average molecular weight: 45,000, acid value: 265 mg KOH / g, non-volatile content: 100%. Copolymer B-3: (Meth)acrylic dispersant with nitrile groups, resin-type dispersant. Weight average molecular weight: 52,000, acid value: 125 mg KOH / g, non-volatile content: 100%. Copolymer B-4: (Meth)acrylic dispersant with nitrile groups, resin-type dispersant. Weight average molecular weight: 52,000, acid value: 78 mg KOH / g, non-volatile content: 100%. BYK-111: DISPERBYK-111 (BYK-Chemie, copolymer with phosphate groups). (Meth)acrylic dispersant with phosphate groups, resin-type dispersant. Weight-average molecular weight: 2000, non-volatile acid value: 129 mg KOH / g, non-volatile content: 95% BYK-190: DISPERBYK-190 (BYK-Chemie, styrene-based block copolymer). A (meth)acrylic dispersant with a carboxyl group, a resin-type dispersant. Weight-average molecular weight: 2400, non-volatile acid value: 10 mg KOH / g, non-volatile content: 40%. Joncryl 63J: BASF Japan, styrene-acrylic acid copolymer. (Meth)acrylic dispersant with neutralized carboxyl groups, resin-type dispersant. Weight-average molecular weight: 12,500, non-volatile acid value: 213 mg KOH / g, non-volatile content: 30% · D331: Spredox D-331 (manufactured by DOXA, a polyether compound having an acidic group and an amine-based functional group). An amphoteric resin-type dispersant. Weight-average molecular weight 23,000, acid value 12 mg KOH / g, amine value 28 mg KOH / g, active ingredient 100%. · EFKA4701: EFKA PX4701 (manufactured by BASF Japan, an acrylic block copolymer). A (meth)acrylic-based dispersant having a basic group, a resin-type dispersant. Weight-average molecular weight 23,000, amine value 40 mg KOH / g, non-volatile content 100%. · CMC: Sunrose APP-84 (manufactured by Nippon Paper Industries Co., Ltd., sodium carboxymethyl cellulose). An anionic resin-type dispersant. Weight-average molecular weight 18,000, non-volatile content 100%. · K30: Polyvinylpyrrolidone K30 (manufactured by Nippon Shokubai Co., Ltd., polyvinylpyrrolidone, weight-average molecular weight 40,000). A nonionic resin-type dispersant.

[0162] <Dispersion medium (C)> · Water: Ion-exchanged water · IPA: Isopropyl alcohol [[ID=1—6]]· n-Butanol·PG: Propylene glycol · Butyl cellosolve: Ethylene glycol mononormal butyl ether

[0163] <pH adjuster (D)> · Sodium hydroxide · Potassium hydroxide

[0164] <Resin (E)> · NANOCRYL-S KPX-02-014: Acrylic resin emulsion, manufactured by Toyochem Co., Ltd. Non-volatile content 40% by mass. · Pes resin A-124GP: Polyester resin emulsion, manufactured by Takamatsu Oil & Fat Co., Ltd. Non-volatile content 30% by mass. · Take lac W-6110: Polyurethane resin emulsion, manufactured by Mitsui Chemicals, Inc. Non-volatile content 32% by mass. · Arrow base SB-1230N: Polyolefin resin emulsion, manufactured by Unitika Ltd. Non-volatile content 25%. Water-based Nigori Clear: Neo Water-Based Nigori Clear, manufactured by Rock Paint. Non-volatile content: 20%. Cymel 325: Melamine resin, manufactured by Mitsui Cytec Co., Ltd. 100% non-volatile content.

[0165] <Non-conductive particles (F)> NK-8G: Synthetic mica (synthetic fluorophlogopite), manufactured by Nihon Koken Kogyo Co., Ltd. Average primary particle size: 8 μm. F-1: Ultrafine zinc oxide, manufactured by Hakusui Tech Co., Ltd. Average primary particle size: 0.1 μm, specific gravity: 5.6 g / cm 3 , specific surface area 10m 2 / g. TTO-51(A): Fine particle titanium dioxide, manufactured by Ishihara Sangyo Kaisha. Average primary particle diameter 0.02 μm, rutile crystal, titanium purity 80%, specific surface area 80 m 2 / g. ABL-412HP: High coloring power black iron oxide, manufactured by Titan Kogyo Co., Ltd. Average primary particle size: 0.1 μm. LIONOL BLUE FG-7351: Copper phthalocyanine pigment (CI Pigment Blue 15:3), manufactured by Toyocolor Co., Ltd. Specific surface area: 68 m 2 / g.

[0166] <Neutralizer (G)> Acetic acid

[0167] <Other additives> Antifoaming agent: BYK-024 (a silicone-based antifoaming agent for water-based systems, manufactured by BYK-Chemie).

[0168] (Measurement of the amount of metal components contained in carbon-based conductive material (A)) Measurement samples were prepared by microwave pressure decomposition as follows, and measurements were performed by high-frequency inductively coupled plasma optical emission spectroscopy (ICP-OES). 50 mg of carbon-based conductive material (A) was precisely weighed into a Teflon (registered trademark) pressure decomposition vessel, and 5 mL of nitric acid (concentration 65% by mass) and 10 mL of perchloric acid (concentration 70% by mass) were added. The mixture was then heated at 120°C for 15 minutes using a microwave pressure decomposition device, and then further heated at 170°C for 30 minutes to obtain a decomposition liquid (measurement sample) in which the carbon-based conductive material (A) had completely dissolved. If a trace amount of insoluble residue remained after dissolution, the insoluble residue was removed by filtration using a membrane filter, and the resulting solution could be used as a measurement sample. The digested solution was then analyzed using an ICP optical emission spectrometer (Agilent 5800 ICP-OES, multi-type, argon plasma light source), and the concentration of each metal in the digested solution was calculated using the absolute calibration curve method. For the analytical values ​​of each metal element, emission lines that are not affected by coexisting elements were used. For example, emission lines with wavelengths of 239 nm and 259 nm can be used for iron, 206 nm and 267 nm for chromium, and 203 nm and 281 nm for molybdenum. The average values ​​obtained at these wavelengths are used in Table 1. The amount of each metal contained in the carbon-based conductive material (A) was calculated from the concentration of each metal contained in the decomposition liquid, and this was taken as the amount of metal component contained in the carbon-based conductive material (A). The amounts of metal components contained in the carbon-based conductive material (A) obtained in this manner are shown in Table 1. Note that the metal contents in Table 1 are in mass%, and "-" indicates that the content is 0.001 mass% or less.

[0169] [Table 1]

[0170] The values ​​in the table are in percentages. Copolymers B-1 to B-4 were synthesized according to the following production examples.

[0171] (Production Example 1: Synthesis of Copolymer B-1) A reaction vessel equipped with a gas inlet tube, thermometer, condenser, and stirrer was charged with 100 parts methyl ethyl ketone, 78.0 parts acrylonitrile, 22.0 parts acrylic acid, and 0.5 parts 3-mercapto-1,2-propanediol, and then purged with nitrogen gas. The reaction vessel was heated to 70°C, and a mixture consisting of 10 parts methyl ethyl ketone and 0.4 parts 2,2'-azobis(2,4-dimethylvaleronitrile) (V-65, Fujifilm Wako Pure Chemical Industries, Ltd.) was added dropwise over 6 hours to carry out the polymerization reaction. After the addition, the mixture was reacted at 70°C for 1 hour, after which 0.1 parts V-65 was added, and the reaction was continued at 70°C for another 1 hour to obtain the product as a precipitate. Measurement of the nonvolatile content confirmed that the conversion rate exceeded 98%. The product was filtered off under reduced pressure, washed with 100 parts ethyl acetate, and dried under reduced pressure to completely remove the solvent, yielding copolymer B-1. The weight average molecular weight of the copolymer B-1 was 25,000. The acid value was 175 mg KOH / g. Next, 2 parts of copolymer B-1, 0.5 parts of sodium hydroxide as pH adjuster (D), and 96.9 parts of purified water were charged into a beaker, and the mixture was stirred at 25°C and a disperser rotation speed of 500 rpm for 15 minutes to carry out a neutralization reaction, thereby obtaining a 10% by mass aqueous solution of copolymer B-1.

[0172] (Production Examples 2 to 4: Synthesis of Copolymers B-2 to B-4) Each copolymer was synthesized in the same manner as in Production Example 1, except that the amounts of acrylonitrile and acrylic acid used were changed according to Table 2, and neutralized with pH adjuster (D) to prepare a 10% by mass aqueous solution. The weight average molecular weight and acid value (mg / KOH) of each copolymer were as shown in Table 2. The amounts of acrylonitrile and acrylic acid shown in Table 2 are expressed in units of % by mass. The amount of neutralizer (D) used indicates the amount of neutralizer (D) used per part of copolymer.

[0173] [Table 2]

[0174] (Method for measuring the acid value of dispersant (B)) The acid value of the dispersant (B) was calculated by titration of an N-methyl-2-pyrrolidone solution of the dispersant (B). 1 g of dispersant (B) was placed in a 100 ml beaker, 30 ml of N-methyl-2-pyrrolidone was added, and the mixture was stirred with a stirrer to dissolve. The mixture was then diluted with 20 ml of ion-exchanged water to prepare a titration solution. This titration solution was titrated with a 0.1 mol / L KOH / ethanol solution using an automatic potentiometric titrator (AT-710S, Kyoto Electronics Manufacturing Co., Ltd.), and the acid value (mg KOH / g) of dispersant (B) was calculated from the titration amount at the isoelectric point.

[0175] (Method for measuring weight-average molecular weight) The weight average molecular weight of the dispersant (B) was measured by gel permeation chromatography (GPC) equipped with a differential refractive index (RI) detector. The equipment used was a HLC-8320GPC (manufactured by Tosoh Corporation), with three separation columns connected in series, and the packing materials used were, in order, Tosoh Corporation's "TSK-GELSUPER AW-4000" and "AW-300 Measurements were performed using "AW-2500" and "AW-2500" at an oven temperature of 40°C, using an N,N-dimethylformamide solution containing 30 mM triethylamine and 10 mM LiBr as the eluent, and at a flow rate of 0.6 ml / min. A solution of dispersant (B) was prepared in the eluent to give a concentration of 1% by mass, and 20 microliters was injected. The molecular weight is a value converted into standard polystyrene.

[0176] <Production of Conductive Dispersion Liquid (1)> [Example 1-1] A mixed solution was prepared by mixing 0.5 parts of ATHLOS as multi-walled carbon nanotubes (A-1), 25 parts of a 10% by mass neutralized aqueous solution of copolymer B-1 as dispersant (B), 0.1 parts of BYK-024 as antifoaming agent, and 74.4 parts of water as dispersion medium (C). The pH of the mixed solution was 12.1. This mixture was dispersed in a colloid mill (IKA Magic LAB) for 30 minutes, and then dispersed 10 times using a high-pressure homogenizer (Sugino Machine Starburst Lab, single nozzle chamber) at a spray pressure of 100 MPa to obtain a dispersion. Furthermore, 7 parts of 0.1 M acetic acid as a neutralizer (G) and 23 parts of water were added to this dispersion and mixed with a disper to obtain 130 parts of a conductive material dispersion (Fa-1). At this time, the pH of the conductive material dispersion (Fa-1) was 9.1.

[0177] [Examples 1-2 to 1-14, Comparative Examples 1-1 to 1-4] Conductive material dispersions Fa-2 to Fa-18 were obtained in the same manner as in Example 1-1, except that the types and amounts of the carbon-based conductive material (A) and dispersant (B) were changed as shown in Table 3-1. Note that the blending amount of the dispersant in Table 3-1 is a value converted into nonvolatile content, and the remainder of the total amount is water, which is the dispersion medium (C). In addition, the pH before the dispersion treatment (corresponding to the timing of step (a)) and the pH after the dispersion treatment (corresponding to the timing of step (b)) were adjusted using acetic acid as a neutralizer (G) so that they would each be the pH values ​​shown in Table 3-2. In Table 3-2, the pH in step (b) marked "-" indicates that no pH adjustment was performed after the dispersion treatment.

[0178] <Evaluation of Conductive Dispersion Liquid (1)> The conductive material dispersions produced in Production of Conductive Material Dispersion (1) were evaluated by the following methods.

[0179] (viscosity) The viscosity was measured immediately after stirring the conductive material dispersion at a rotation speed of 1000 rpm for 5 minutes using a disper. The viscosity was measured for the conductive material dispersion at a liquid temperature of 25°C using a B-type viscometer ("BL" manufactured by Toki Sangyo Co., Ltd.) for a measurement time of 1 minute. Note that the measurement was first performed with the rotor rotation speed of the viscometer at 6 rpm, and then at 60 rpm. For measurements at a rotor rotation speed of 6 rpm, rotor No. 1 was used when the viscosity was less than 1.0 Pa·s, No. 2 when the viscosity was 1.0 Pa·s or more but less than 5.0 Pa·s, No. 3 when the viscosity was 5.0 Pa·s or more but less than 20 Pa·s, and No. 4 when the viscosity was 20 Pa·s or more but less than 100 Pa·s. For measurements at a rotor speed of 60 rpm, rotor No. 1 was used when the viscosity was less than 0.1 Pa·s, No. 2 when the viscosity was 0.1 Pa·s or more but less than 0.5 Pa·s, No. 3 when the viscosity was 0.5 Pa·s or more but less than 2.0 Pa·s, and No. 4 when the viscosity was 2.0 Pa·s or more but less than 10 Pa·s. The viscosity was measured within 5 hours after the completion of the dispersion treatment (hereinafter, this viscosity is referred to as "initial viscosity").

[0180] (TI value) The TI value was calculated from the measured viscosity value using the following formula (1). Equation (1) TI value = (viscosity measured at 6 rpm / viscosity measured at 60 rpm) [Evaluation criteria] ◎: TI value is 3 or more and 10 or less (best) ○: TI value is 2 or more and less than 3 (good) ×: TI value is less than 2 (bad)

[0181] (Storage stability (S1)) The storage stability was evaluated by observing the change in viscosity (viscosity change rate) when the conductive material dispersion was measured at a rotor rotation speed of 60 rpm after being left to stand and stored at 60°C for 10 days. The viscosity change rate was calculated using the following formula (2). Rate of change (%) = (viscosity after 10 days at 60℃) / (initial viscosity) x 100...Equation (2) [Evaluation criteria] ◎: Change rate is 85% or more but less than 115% (best) ○: The rate of change is 75% or more but less than 85% or 115% or more but less than 125% (good). △: Change rate is 50% or more but less than 75% or 125% or more but less than 150% (acceptable) ×: Change rate is less than 50% or more than 150% (bad)

[0182] (dispersibility) The evaluation of dispersibility was carried out in accordance with JIS-K5600-2-5 using a grind gauge with a maximum groove depth of 300 μm. The evaluation criteria are as follows: [Evaluation criteria] ○: No coarse particles (best) △: Coarse particles less than 100 μm (acceptable) ×: Coarse particles of 100 μm or more are present (defective)

[0183] (Conductive R1) The electrical conductivity R1 was evaluated by measuring the electrical conductivity of a coating film applied to a polyethylene terephthalate (PET) film. The conductive material dispersion was applied onto a PET film using a 7-mil applicator, leveled at 20°C for 10 minutes, and then dried at 100°C for 20 minutes to obtain a coating film. The coating film was evaluated by measuring the surface resistivity (Ω / □) using a resistivity meter Loresta-GX MCP-T700 (manufactured by Mitsubishi Chemical Analytech Co., Ltd., four-point probe method), and the evaluation was performed according to the following criteria. [Evaluation criteria] ◎: 1.0×10 3 Below (best) ○:1.0×10 3 Super 1.0×10 4 Below (good) △:1.0×10 4 Super 1.0×10 5 Below (possible) ×:1.0×10 5 Super (poor)

[0184] (Lightness L1) The lightness L1 was evaluated by measuring the lightness L* in the L*a*b* color system using a spectro2guide (spectrophotometer / color difference meter) manufactured by BYK-Gardner for the coating film applied to the PET film, and the result was taken as the lightness L1. The coating film used was the same as that prepared for the evaluation of conductivity. Evaluation was carried out according to the following criteria: [Evaluation criteria] ◎: 5 to 20 (best) 〇: 3 or more but less than 5, or 20 or more but less than 23 (good) △: 0 or more but less than 3, or 23 or more but less than 25 (acceptable) ×: Less than 0 or 25 or more (bad)

[0185] (chromaticity b1) The chromaticity b1 was evaluated by measuring the chromaticity b* of the coating film applied to the PET film in the L*a*b* color system using a BYK-Gardner spectro2guide (spectrophotometer / color difference meter), and the chromaticity b1 was determined. The coating film used was the same as that prepared for the conductivity evaluation. Evaluation was carried out according to the following criteria. [Evaluation criteria] ◎: 1 or less (best) 〇: More than 1 and less than 2 (good) △: More than 2 and less than 3 (acceptable) ×: Exceeding 3 (defect)

[0186] (50% particle size (D50)) The 50% particle size (D50) of the conductive material dispersion was measured using a laser diffraction particle size distribution analyzer (Microtrac MT3000II, manufactured by Microtrac-Bell) by the following method, and the evaluation was performed according to the following criteria. First, 0.5 g of the conductive material dispersion was diluted with 30 g of water and then treated with an ultrasonic homogenizer (output 100 W) for 5 minutes to prepare a measurement sample. Next, 1 to 10 drops of the measurement sample were poured into a measurement cell and diluted with a sufficient amount of water. The particle size distribution was measured at 25°C and analyzed with a particle refractive index of 1.746 and a solvent refractive index of 1.33. The particle size corresponding to 50% of the cumulative value (volume basis) in the obtained particle size distribution was defined as the 50% particle size (D50). [Evaluation criteria] ◎: 30μm or more and 130μm or less (best) ○: 20 μm or more and less than 30 μm, or more than 130 μm and less than 140 μm (good) △: 10 μm or more and less than 20 μm, or 140 μm or more and 150 μm or less (acceptable) ×: Less than 10 μm or more than 150 μm (defective)

[0187] The conductive dispersions obtained in Examples 1-1 to 1-14 all had good dispersibility, TI value, and storage stability, and also had good conductivity when coated. On the other hand, the dispersions obtained in Comparative Examples 1-1 to 1-4 all had poor properties, and it can be seen that particularly good dispersions are obtained when multi-walled carbon nanotubes (A-1) are used as the carbon-based conductive material (A). In Table 3-2, the marks "-" indicate that the dispersions were poor and could not be evaluated. Furthermore, Examples 1-1 to 1-14 show that various dispersants can be used as the dispersant (B), and that particularly good results can be obtained when a polymer dispersant having an acidic group is used.

[0188] [Table 3-1]

[0189] [Table 3-2]

[0190] <Production of Conductive Dispersion Liquid (2)> [Example 2-1] A mixed solution was prepared by mixing 0.5 parts of ATHLOS as multi-walled carbon nanotubes (A-1), 12.5 parts of a 10% by weight neutralized aqueous solution of copolymer B-1, 0.1 parts of BYK-024 as an antifoaming agent, and 86.9 parts of purified water, and the pH of the mixed solution was 11.7. This mixture was dispersed in a colloid mill (IKA Magic LAB) for 30 minutes, and then dispersed 10 times using a high-pressure homogenizer (Sugino Machine Starburst Lab, single nozzle chamber) at a spray pressure of 100 MPa to obtain a dispersion. Further, 7 parts of 0.1 M acetic acid and 23 parts of purified water were added to this dispersion and mixed using a disper to obtain 130 parts of a conductive material dispersion (Fb-1), which had a pH of 9.6.

[0191] [Examples 2-2 to 2-9] Conductive material dispersions Fb-2 to Fb-9 were obtained in the same manner as in Example 2-1, except that the types and amounts of the carbon-based conductive material (A), dispersant (B), and dispersion medium (C) were changed so as to be blended in amounts as shown in Table 4-1. Note that the blending amounts of the dispersant in Table 4-1 are values ​​converted into nonvolatile content, and the remainder of the total amount is water. In addition, the pH before the dispersion treatment (corresponding to the timing of step (a)) and the pH after the dispersion treatment (corresponding to the timing of step (b)) were adjusted to the pH values ​​shown in Table 4-2 using acetic acid as a neutralizer (G).

[0192] <Evaluation of Conductive Dispersion Liquid (2)> The conductive material dispersion prepared in Preparation of Conductive Material Dispersion (2) was evaluated in the same manner as in Evaluation of Conductive Material Dispersion (1).

[0193] The conductive dispersions obtained in Examples 2-1 to 2-9 all had good dispersibility, TI value, and storage stability, and also had good conductivity when coated.

[0194] [Table 4-1]

[0195] [Table 4-2]

[0196] <Production of Conductive Dispersion Liquid (3)> [Example 3-1] A mixed solution was prepared by mixing 0.5 parts of ATHLOS as multi-walled carbon nanotubes (A-1), 25 parts of a 10% by mass neutralized aqueous solution of copolymer B-1, 0.1 parts of BYK-024 as an antifoaming agent, and 74.4 parts of purified water, and the pH of the mixed solution was 12.1. This mixture was dispersed in a colloid mill (IKA Magic LAB) for 30 minutes to obtain a dispersion. 15 parts of 0.1 M acetic acid and 15 parts of purified water were added to 100 parts of this dispersion and mixed using a disperser to obtain a conductive material dispersion (Fc-1). At this time, the pH of the conductive material dispersion (Fc-1) was 9.1.

[0197] [Example 3-2] A mixed solution was prepared by mixing 0.5 parts of ATHLOS as multi-walled carbon nanotubes (A-1), 25 parts of a 10% by mass neutralized aqueous solution of copolymer B-1, 0.1 parts of BYK-024 as an antifoaming agent, and 74.4 parts of purified water, and the pH of the mixed solution was 12.1. This mixture was subjected to ultrasonic dispersion treatment for 30 minutes using an ultrasonic disperser (Hielscher UP400S) to obtain a dispersion. 15 parts of 0.1 M acetic acid and 15 parts of purified water were added to 100 parts of this dispersion and mixed using a disperser to obtain a conductive material dispersion (Fc-2). At this time, the pH of the conductive material dispersion (Fc-2) was 9.0.

[0198] [Example 3-3] A mixed solution was prepared by mixing 0.5 parts of ATHLOS as multi-walled carbon nanotubes (A-1), 25 parts of a 10% by mass neutralized aqueous solution of copolymer B-1, 0.1 parts of BYK-024 as an antifoaming agent, and 74.4 parts of purified water, and the pH of the mixed solution was 12.1. 200 g of 0.5 mm diameter zirconia beads were added to this mixture as a dispersion medium, and the mixture was dispersed for 8 hours using a paint shaker to obtain a dispersion. 15 parts of 0.1 M acetic acid and 15 parts of purified water were added to 100 parts of this dispersion, and the mixture was mixed using a disperser to obtain a conductive material dispersion (Fc-3). At this time, the pH of the conductive material dispersion (Fc-3) was 8.9.

[0199] [Example 3-4] A mixed solution was prepared by mixing 0.5 parts of ATHLOS as multi-walled carbon nanotubes (A-1), 25 parts of a 10% by mass neutralized aqueous solution of copolymer B-1, 0.1 parts of BYK-024 as an antifoaming agent, and 74.4 parts of purified water, and the pH of the mixed solution was 12.1. This mixture was subjected to a dispersion treatment for 30 minutes using a colloid mill (IKA Magic LAB) to obtain a dispersion. 28 parts of purified water was added to 100 parts of this dispersion and mixed using a disperser to obtain 130 parts of conductive material dispersion (Fc-4). At this time, the pH of the conductive material dispersion (Fc-4) was 11.7.

[0200] [Examples 3-5] Dispersant (B) copolymer B-1 2 parts, neutralizer (G) acetic acid 10 parts, purified water 97.3 parts, 25 ° C, disperser rotation speed 500 rpm, stirred for 15 minutes neutralized solution, multi-walled carbon nanotube (A-1) ATHLOS 0.5 parts, antifoaming agent BYK-024 0.1 parts, mixed to prepare a mixed solution. At this time, the pH of the mixed solution was 6.8. This mixture was subjected to a dispersion treatment for 30 minutes using a colloid mill (IKA Magic LAB) to obtain a dispersion. 3 parts of 0.1 M acetic acid and 27 parts of purified water were added to 100 parts of this dispersion and mixed using a disperser to obtain 130 parts of a conductive material dispersion (Fc-5). At this time, the pH of the conductive material dispersion (Fc-5) was 5.8.

[0201] The amounts of dispersants in Table 5-1 are calculated as nonvolatile content, and the remainder of the total amount is water.

[0202] <Evaluation of Conductive Dispersion Liquid (3)> The conductive material dispersion produced in Production of Conductive Material Dispersion Liquid (3) was evaluated in the same manner as in Evaluation of Conductive Material Dispersion Liquid (1), except for the following points. That is, the storage stability test method was changed to a method in which the prepared conductive material dispersion liquid was placed in a vial, and the state of separation of the dispersion liquid after leaving it to stand at 40°C for 10 days was evaluated visually. Hereinafter, the storage stability test carried out in this manner will be referred to as Storage Stability Test (S2). The storage stability test (S2) was evaluated according to the following criteria. [Evaluation criteria] 〇: No change (good) △: The supernatant is clear. (Acceptable) ×: Settled or separated (unacceptable)

[0203] The conductive dispersions obtained in Examples 3-1 to 3-5 all had good dispersibility, TI value, and storage stability, and also had good conductivity when coated. Examples 3-1 to 3-4 show that particularly good dispersions can be obtained when a rotor-stator type disperser, ultrasonic disperser, or high-pressure homogenizer is used as the dispersing machine. Furthermore, Examples 3-1 and 3-4 to 3-5 show that a particularly good dispersion state can be obtained by including step (a).

[0204] [Table 5-1]

[0205] [Table 5-2]

[0206] <Production of Conductive Material Dispersion Containing Resin (E) and Conductive Film (1)> [Example 4-1] The conductive material dispersion Fa-1 obtained in Example 1-1, clear coating material A, and purified water were blended according to the following composition to obtain a conductive material dispersion containing a resin (E). Conductive material dispersion Fa-1: 3.64 parts Clear paint A = (water-based Nigori Clear / Cymel 325 = 75% by weight / 25% by weight): 10 parts Purified water: 1.08 parts Next, the obtained conductive material dispersion containing resin (E) was applied to a corona discharge-treated PET film using an applicator to a film thickness of 20±2 μm, and after leveling for 30 minutes, it was dried at 60°C for 30 minutes and then baked at 140°C for 20 minutes to obtain conductive film Pa-1.

[0207] [Examples 4-2 to 4-11, Comparative Examples 4-1 to 4-3] Conductive films Pa-2 to Pa-11 and Pb-1 to Pb-3 were obtained in the same manner as in Example 4-1, except that the types and amounts of conductive material dispersion, clear coating material A, and purified water were changed as shown in Table 6.

[0208] <Evaluation of Conductive Film (1)> The conductive material dispersion containing resin (E) and the conductive film produced in Production of Conductive Film (1) were evaluated by the following methods.

[0209] (compatibility) The compatibility was evaluated by measuring the haze (Hz) of the prepared conductive film using NDH8000 (manufactured by Nippon Denshoku Industries Co., Ltd.) and was evaluated according to the following criteria. [Evaluation criteria] ○: Less than 5 △: 5 or more but less than 10 ×: 10 or more

[0210] (transparency) The transparency of the conductive film was evaluated by measuring the total light transmittance (TT) of the prepared conductive film using a haze meter NDH8000 (manufactured by Nippon Denshoku Industries Co., Ltd.). The evaluation was performed according to the following criteria. [Evaluation Criteria] ◎: 40 or above (best) 〇: 35 or more and less than 40 (good) △: 30 or over but under 35 (acceptable) ×: Less than 30 (bad)

[0211] (Conductivity R2) The electrical conductivity R2 was evaluated by measuring the surface resistivity (Ω / □) of the prepared conductive film using a resistivity meter, Hiresta UX MCP-HT800 (manufactured by Mitsubishi Chemical Corporation). The evaluation was carried out according to the following criteria. [Evaluation criteria] ◎: 1.0×10 6 Less than (best) ○:1.0×10 6 Over 1.0 x 10 8 Less than (good) △:1.0×108 Over 1.0 x 10 10 Less than (acceptable) ×:1.0×10 10 or more (defect)

[0212] The conductive films obtained in Examples 4-1 to 4-11 all had good compatibility, transparency, and conductivity, whereas the conductive films obtained in Comparative Examples 4-1 to 4-3 all had poor properties, indicating that a particularly good conductive film can be obtained when multi-walled carbon nanotubes (A-1) are used as the carbon-based conductive material (A).

[0213] [Table 6]

[0214] <Production of Conductive Material Dispersion Containing Resin (E) and Conductive Film (2)> [Example 5-1] The conductive material dispersion Fa-7 obtained in Example 1-7, the dispersion medium (C), and the resin (E) were blended according to the following composition to obtain a conductive material dispersion containing the resin (E). Conductive dispersion Fa-7: 8.2 parts Dispersion medium (C): water 9.1 parts Resin (E): NANOCRYL-S KPX-02-014 10 parts Next, the obtained conductive material dispersion containing resin (E) was applied to a corona discharge-treated PET film using an applicator to a film thickness of 20±2 μm, and after leveling for 30 minutes, it was dried at 60°C for 30 minutes and then baked at 140°C for 20 minutes to obtain conductive film Pc-1.

[0215] [Examples 5-2 to 5-8] Conductive films Pc-2 to Pc-8 were obtained in the same manner as in Example 5-1, except that the types and amounts of the conductive material dispersion, dispersion medium (C), and resin (E) were changed as shown in Table 7. In Table 7, the marks "-" indicate that the non-conductive particles (F) were not added.

[0216] [Examples 5-9] The conductive material dispersion Fa-7 obtained in Example 1-7, the dispersion medium (C), the resin (E), and the non-conductive particles (F) were blended according to the following composition to obtain a conductive material dispersion containing the resin (E) and the non-conductive particles (F). Conductive dispersion Fa-7: 7.6 parts Dispersion medium (C): water 7.7 parts Resin (E): Takelac W-6110 10 parts Non-conductive particles (F): NK-8G 0.5 part Next, the obtained conductive material dispersion containing resin (E) and non-conductive particles (F) was applied to a corona discharge-treated PET film using an applicator to a film thickness of 20±2 μm, and after leveling for 30 minutes, it was dried at 60°C for 30 minutes and then baked at 140°C for 20 minutes to obtain conductive film Pc-9.

[0217] [Examples 5-10 to 5-13] Conductive films Pc-10 to Pc-13 were obtained in the same manner as in Example 5-9, except that the types and amounts of the conductive material dispersion, dispersion medium (C), resin (E), and non-conductive particles (F) were changed as shown in Table 7.

[0218] The conductive material dispersions obtained in Examples 5-1 to 5-13 were all easy to mix, and even after mixing, the viscosity and storage stability were not impaired, and they were in good condition. In addition, the conductive films obtained in Examples 5-1 to 5-13 all had good appearances. These results show that various resins and non-conductive particles can be blended into the conductive material dispersions.

[0219] [Table 7]

Claims

1. A conductive material dispersion containing a carbon-based conductive material (A), a dispersant (B), and a dispersion medium (C), The carbon-based conductive material (A) contains multi-walled carbon nanotubes (A-1), A conductive material dispersion liquid in which the iron content in the multi-walled carbon nanotubes (A-1) is more than 0 mass% and 5 mass% or less, and the total content of cobalt and molybdenum is 0 mass% or more and 0.1 mass% or less.

2. The specific surface area of ​​the multi-walled carbon nanotube (A-1) is 400 m ２ The conductive material dispersion according to claim 1, wherein the surface area of ​​the conductive material dispersion is 1 / g or less.

3. 2. The conductive material dispersion according to claim 1, wherein the multi-walled carbon nanotubes (A-1) have an average aspect ratio of 300 or more and 2000 or less.

4. 2. The conductive material dispersion according to claim 1, wherein the multi-walled carbon nanotubes (A-1) have an average outer diameter of 5 nm or more and 30 nm or less.

5. 2. The conductive material dispersion according to claim 1, wherein the content of the nonvolatile component is 0.01% by mass or more and 5% by mass or less based on 100% by mass of the nonvolatile component of the conductive material dispersion.

6. The conductive material dispersion liquid according to any one of claims 1 to 5, wherein the dispersant (B) comprises at least one dispersant selected from the group consisting of a nonionic dispersant, an anionic dispersant, a cationic dispersant, and an amphoteric dispersant.

7. The conductive material dispersion according to any one of claims 1 to 5, wherein the conductive dispersion has a thixotropic index of 2 or more and 10 or less.

8. The conductive material dispersion according to any one of claims 1 to 5, wherein the conductive dispersion has a D50 particle size of 10 µm or more and 150 µm or less.

9. The conductive material dispersion according to any one of claims 1 to 5, further comprising a resin (E).

10. The conductive material dispersion according to any one of claims 1 to 5, further comprising non-conductive particles (F).

11. The conductive material dispersion according to claim 9, wherein the content of the carbon-based conductive material (A) is 0.01% by mass or more and 3% by mass or less, based on 100% by mass of the nonvolatile content of the conductive material dispersion.

12. A conductive film containing a carbon-based conductive material (A), a dispersant (B), and a resin (E), The carbon-based conductive material (A) contains multi-walled carbon nanotubes (A-1), A conductive film, wherein the iron content in the multi-walled carbon nanotubes (A-1) is more than 0 mass % and 5 mass % or less, and the total content of cobalt and molybdenum is 0 mass % or more and 0.1 mass % or less.

13. The conductive film according to claim 12, wherein the resin (E) is a binder resin.

14. A method for producing a conductive material dispersion liquid obtained by dispersing a mixture containing a carbon-based conductive material (A), a dispersant (B), and a dispersion medium (C) using a media-less disperser selected from the group consisting of a rotor-stator type disperser, an ultrasonic disperser, and a high-pressure homogenizer, comprising: The carbon-based conductive material (A) contains multi-walled carbon nanotubes (A-1), A method for producing a conductive material dispersion, wherein the iron content in the multi-walled carbon nanotubes (A-1) is more than 0 mass% and 5 mass% or less, and the total content of cobalt and molybdenum is 0 mass% or more and 0.1 mass% or less.

15. A method for producing a conductive material dispersion liquid containing a carbon-based conductive material (A), a dispersant (B), and a dispersion medium (C), comprising: The carbon-based conductive material (A) contains multi-walled carbon nanotubes (A-1), A method for producing a conductive material dispersion, wherein the iron content in multi-walled carbon nanotubes (A-1) is more than 0 mass% and 5 mass% or less, and the total content of cobalt and molybdenum is 0 mass% or more and 0.1 mass% or less, and the method comprises the following step (a): Step (a): A step of mixing a carbon-based conductive material (A), a dispersant (B), and a dispersion medium (C) to prepare a mixed liquid, and then dispersing the mixed liquid at a pH of 7 or higher.

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